PURPOSE: To find incorrect mounting direction of an electronic part immediately by bending a lead at different positions in right and left sides of a main body and by attaching a mark of the electronic part on a printed substrate to show a mounting position of the electronic part.

CONSTITUTION: Incorrect mounting of an electronic part 2 can be immediately found by a mark to prevent mounting of the electronic part 2 in a reverse direction. That is, in the part 2, a lead line 3 is bent what is called unsymmetrically, long in the right and short in the left. Meanwhile, a mark 5 to show a mounting position of the part 2 is printed in advance on a printed board 1, and an operator inserts the part 2 to a part mounting hole 4 in accordance with the marking. In the process, if the part 2 is mounted reversely by mistake, the electronic part main body 2 and the mark 5 of the printed substrate do not coincide each other. Therefore, incorrect mounting can be discriminated at a glance.