On a surface layer of a printed wiring board, main power supply patterns to be applied with different DC voltages are disposed in a second region. Power supply patterns are disposed on the surface layer, and the power supply patterns are led from the main power supply patterns to a first region. The power supply patterns connect power supply terminals of terminal groups in the second region. The power supply patterns connect the power supply terminals between the terminal groups in the first region. Power supply terminals of the terminal groups of a semiconductor package are electrically connected to the main power supply patterns by the power supply patterns. Thus, potential fluctuations are reduced and radiation noise is suppressed, and the number of layers of the printed wiring board is reduced.