To mount a BGA package manually on a printed wiring board by disposing a mounting jig inserting part for regulating the position of a mounting jig in the vicinity of a BGA package mounting position on a printed wiring board.

The footprint 2 of a printed wiring board 1 is previously coated with cream solder 3 and a solder ball 7 is set previously on the electrode 6 of a BGA(ball grid array) package 5. A mounting jig 11 comprises a BGA package regulating part 12 corresponding to the external dimensions of the BGA package 5 for regulating the position of the BGA package 5 and the mounting jig 11, and a columnar mounting jig fixing part 13 being inserted into the printed wiring board 1. Furthermore, the printed wiring board 1 is provided with a mounting jig inserting part 4 for inserting the mounting jig fixing part 13 such that the footprint 2 of the printed wiring board 1 faces the electrode 6 of the BGA package 5 being regulated positionally to the mounting jig 11.