1. An operation supporting device that provides a user with information on an operation for executing a function desired by the user from among functions of each apparatus of a plurality of apparatuses connected to a network, said operation supporting device comprising: an operation history collecting unit configured to collect, from each apparatus of the plurality of apparatuses, operation history information including operation histories describing time-series information of operations performed by the user during a time period preceding a predetermined time period from a time when the user requests support; an apparatus information storage unit configured to store function description information including descriptions of the functions of each apparatus of the plurality of apparatuses; a confusion definition information storage unit configured to store confusion definition information defining, as confused operations, operations performed when the user is confused due to an inability to execute the function desired by the user; a to-be-supported apparatus estimating unit configured to determine, for each apparatus of the plurality of apparatuses and with reference to the confusion definition information stored in said confusion definition information storage unit, a respective degree of matching between (i) an operation history of the operation histories included in the operation history information collected by said operation history collecting unit and (ii) a confused operation of the confused operations defined in the confusion definition information, and configured to estimate that an apparatus of the plurality of apparatuses, which is determined to have the respective degree of matching exceeding a predetermined threshold, is an apparatus having a high requirement for support in order for the user to perform the operations; and a function description output unit configured to output at least one description of the descriptions of the functions of the apparatus estimated as having the high requirement for the support, with reference to the function description information stored by said apparatus information storage unit.