A pressure sensor chip includes a diaphragm and pads. A flexible printed circuit board (FPC) includes a resin sheet having a through-hole and wiring patterns that are formed within the resin sheet and sealed. The resin sheet is press-fitted to the pressure sensor chip such that the diaphragm is bared at the through-hole. The wiring patterns are connected to the pads, and junctions between the wiring patterns and the pads are sealed with the resin sheet.