as shown in fig1 an automobile 1 includes a front windshield 3 positioned in front of front seats 2 including driver and passenger seats 4 , 5 . the automobile 1 also has an instrument panel 6 positioned in front of the front seats 2 and extending fully across the automobile , a steering wheel 7 positioned in front of the driver seat 4 , a plurality of meters 8 on a region of the instrument panel 6 in front of the steering wheel 7 , and a center console 9 located between the driver and passenger seats 4 , 5 . an air bag device ( not shown ) associated with the driver seat 4 is disposed centrally in the steering wheel 7 , and an air bag device 15 ( see fig2 and 3 ) associated with the passenger seat 5 is disposed in a region of the instrument panel 6 in front of the passenger seat 5 . as shown in fig2 and 3 , the instrument panel 6 comprises a baseboard 10 made of hard resin or the like , a cushioning layer 11 applied to a surface of the instrument panel 6 which faces the driver and passenger seats 4 , 5 , and a ornamental covering sheet 12 covering the cushioning layer 11 . the instrument panel 6 has a laterally elongate opening 13 defined in an upper surface thereof in front of the passenger seat 5 , the opening 13 having a step 14 ( see pg , 7 fig3 ) along its edge . the air bag device 15 is stored in the instrument panel 6 through the opening 13 . as shown in fig2 the air bag device 15 includes a laterally elongate casing 16 having an upper opening 17 and comprising a lower case 19 having a bottom panel 18 and a frame - like upper case 20 in which the opening 19 is defined . the lower and upper cases 19 , 20 are removably fastened to each other . the lower case 19 houses therein an inflator 21 whose upper surface is supported by a stay 22 extending across the lower case 19 . an air bag 23 which is folded is stored in the lower and upper cases 19 , 20 above the stay 22 . the lower case 19 has an outwardly bent engaging edge 24 along its upper peripheral edge portion , and the upper case 20 has a lower edge 25 fitted in the engaging edge 24 . the air bag 23 has a peripheral edge 26 clamped between the lower edge 25 of the upper case 20 and the engaging edge 24 of the lower case 19 , and is folded and stored in the casing 16 . a stay 27 is fastened to the bottom panel 18 of the lower case 19 , and also coupled to a stay or the like ( not shown ) joined to the instrument panel 6 . thus , the air bag device 15 is supported by the instrument panel 6 . a lid 28 ( see also fig1 ) is disposed over the upper opening 17 of the casing 16 . the lid 28 is made of the same resin as that of the instrument panel 6 , and has its outer edge fitted in the step 14 of the opening 13 . a core plate 29 is embedded in the lid 28 at a transversely intermediate position therein and has a v - shaped rear portion 30 projecting out of the lid 28 . the projecting rear end portion 30 is fastened by a bolt 33 to a support 32 bent rearwardly from an upper edge of a vertical rear panel 31 of the upper case 20 . a front support flap 34 projects downwardly along an inner edge of the opening 13 in the instrument panel 6 . the front support flap 34 has a recess 35 defined in an upper edge thereof which is joined to a lower surface of the lid 28 , the recess 35 extending in the forward direction of the automobile . the portion of the front support flap 34 below the recess 35 is fastened to an upper portion 37 of a front vertical panel 36 of the upper case 20 by a bolt 38 . the upper edge of the front support flap 34 with the recess 35 serves as a tear - off region which will be forcibly cut off when the air bag 23 is inflated , allowing the air bag 23 to be inflated through the opening 13 toward the passenger seat 5 . the air bag device 15 includes an air bag restraint guide 40 positioned in the opening 13 of the casing 16 along its edge near the passenger compartment of the automobile . the air bag restraint guide 40 is disposed directly below the lid 28 in a region of the casing 16 near the passenger compartment of the automobile . the air bag restraint guide 40 is substantially inverted v - shaped as viewed in side elevation . the air bag restraint guide 40 comprises a substantially vertical base 41 which is also fastened to the upper portion 37 of the front vertical panel 36 by the bolt 38 , and an overhanging member 42 bent substantially at a right angle from an upper edge of the base 41 toward the front windshield and positioned substantially at the same height as the opening 13 . the air bag 23 that is stored in the casing 16 has a portion located below the overhanging member 42 . the air bag restraint guide 40 is in the form of a thin plate made of a resin material such as a thermoplastic elastomer , polypropylene , urethane , or the like , or aluminum alloy , or iron . when the air bag 23 is inflated , the overhanging member 42 is easily bent upwardly by the air bag 23 , and is positioned between the edge of the opening 13 and the inflated air bag 23 . the air bag device 15 operates as follows : when the automobile collides with another automobile or object , the inflator 21 is actuated upon impact to inflate the air bag 23 . the tear - off region including the recess 35 by which the lid 28 is joined to the casing 16 is forcibly cut off , and the lid 28 is lifted by the inflating air bag 23 with the front edge of the lid 28 remaining joined to the casing 16 . while lifting the lid 28 , the air bag 23 is expanded through the openings 17 , 13 into the passenger compartment . at this time , the overhanging member 42 of the air bag restraint guide 40 is forcibly bent upwardly and toward the passenger compartment by contact with the air bag 23 as it is inflated , and is interposed between the edge of the opening 13 near the passenger compartment and the inflating air bag 23 , as shown in fig3 . fig4 through 6 show an air bag device according to another embodiment of the present invention . the air bag device 15 shown in fig4 through 6 employs a protective cloth 140 , which may be either woven or nonwoven , in place of the air bag restraint guide 40 shown in fig2 and 3 . the other structural details including the air bag 23 , the inflator 21 , the casing 16 , the lid 28 , etc . are identical to those of the air bag device 15 shown in fig2 and 3 , and will not be described in detail below . fig4 illustrates the air bag device 15 before the air bag 23 is set in the casing 16 . the air bag 23 has its peripheral edge 26 clamped between the edges 24 , 25 of the lower and upper cases 19 , 20 . the protective cloth 140 has a lower edge 141 clamped between portions 24a , 25a of the edges 24 , 25 near the passenger compartment . the air bag 23 has an intermediate portion 23a folded into a vertical array of layers , and is placed downwardly into an upper portion of the casing 16 through the opening 15 . the protective cloth 140 has a rear portion 142 placed on a lower portion of the air bag 23 near the passenger compartment , and a front portion 143 bent angularly from the rear portion 142 over the upper case 20 and hanging downwardly into the passenger compartment . the air bag 23 is turned clockwise 90 ° from the position shown in fig3 into the position shown in fig4 stored in the casing 16 , covered with the protective cloth 140 , and the lid 28 is joined to the casing 16 over the opening 13 . the air bag 23 is now mounted in the instrument panel 6 as shown in fig4 . when the automobile collides with another automobile or object , the inflator 21 is actuated upon impact to inflate the air bag 23 . the tear - off region including the recess 35 is forcibly cut off , and the lid 28 is lifted by the inflating air bag 23 with the front edge of the lid 28 remaining joined to the casing 16 . while lifting the lid 28 , the air bag 23 is expanded through the openings 17 , 13 into the passenger compartment . at this time , the protective cloth 140 is forcibly flexed upwardly and toward the passenger compartment by contact with the air bag 23 as it is inflated , and is interposed between the edge of the opening 13 near the passenger compartment and the inflating air bag 23 , as shown in fig6 . as described above , when the air bag 23 is inflated , since the air bag restraint guide 40 or the protective cloth 140 is deformed or flexed and positioned between the surface of the air bag 23 and the edge of the opening 13 , the air bag 23 is prevented from interfering directly with the edge of the opening 13 and hence can smoothly be inflated through the opening 13 . therefore , the instrument panel 6 is prevented from being damaged by direct contact with the air bag 23 when it is inflated . the air bag device 15 is relatively simple in structure as it additionally requires only the air bag restraint guide 40 or the protective cloth 140 . the air bag device 15 is relatively inexpensive as it can reliably prevent the air bag 23 from interfering with the edge of the opening 13 with a minimum number of parts . although there have been described what are at present considered to be the preferred embodiments of the invention , it will be understood that the invention may be embodied in other specific forms without departing from the essential characteristics thereof . the present embodiments are therefore to be considered in all respects as illustrative , and not restrictive . the scope of the invention is indicated by the appended claims rather than by the foregoing description .