A differential pressure type high pressure water electrolysis apparatus has a flow passage forming member for supplying water to an anode. In the flow passage forming member, there are formed a water receiving section for receiving water supplied from the exterior, a distributing path for distributing the water that has flowed into the water receiving section, a converging path into which a surplus supplied amount of water flows, and a water discharging section for receiving the water inside the converging path and discharging it to the exterior. The positions of the distributing path and the converging path are offset from an opposing position where a seal member faces toward a pressure resistant member that surrounds the seal member from the exterior.