Water electrolysis device and water electrolysis system using water electrolysis device

A water electrolysis device comprising:

• a water electrolysis stack that includes a cell laminated body in which a plurality of water electrolysis cells is laminated;
• and
• a drain pipe that is connected to the water electrolysis stack, wherein:
• the water electrolysis stack includes
• a hydrogen electrode side manifold through which hydrogen generated by water electrolysis flows,
• an oxygen electrode side manifold through which oxygen generated by the water electrolysis flows, and
• a water supply manifold through which water to be used for the water electrolysis flows;
• the hydrogen electrode side manifold and the oxygen electrode side manifold pass in a lamination direction;
• the drain pipe includes
• a hydrogen electrode side drain pipe that is connected to the hydrogen electrode side manifold,
• an oxygen electrode side drain pipe that is connected to the oxygen electrode side manifold, and
• a connection pipe that connects the hydrogen electrode side drain pipe and the oxygen electrode side drain pipe;
• and
• the connection pipe includes a drain valve that adjusts a flow rate of water that flows through the connection pipe.