In a lead mounting method of mounting, onto a principal surface of a printed board, a lead to be connected to a terminal, a flat lead is prepared which lead has a mounted part to be disposed on the principal surface of the printed board and a connected part to be connected to the terminal. The flat lead is bent into an L shape so that the mounted part and the connected part are perpendicular to each other to obtain an L-shaped lead. The mounted part of the L-shaped lead is connected and fixed onto the principal surface of the printed board by soldering.