1. A method of mounting parts sequentially to a plurality of board blocks formed on a board at a plurality of mounting stages, said method comprising the steps of: (a) obtaining relative positional data of respective recognition points formed on the board by recognizing every recognition point in the board at a first mounting stage; (b) detecting a whole position of the board by recognizing a particular recognition point at a second mounting stage and an onward stage; (c) detecting a positional deviation of the board blocks at the mounting stages based on the whole position and the relative positional data; and (d) mounting the parts to the board blocks correcting the positional deviation.