To improve the connection reliability between a mother board and a printed wiring board.

Diameters of openings 71B1, 71B2, 71B3 of a solder resist layer 70B decrease from a center part of a printed wiring board toward an outer periphery. Height of solder bumps 76D1, 76D2, 76D3, which are respectively provided at the openings 71B1, 71B2, 71B3, increase from the center part to the outer periphery. Even if warpage occurs in the printed wiring board, tops of the solder bumps are substantially aligned on the same plane surface PL.