A valve device includes: a body formed with a valve chamber, a first inflow passage, a second inflow passage, an outflow passage, and an annular groove and provided with a valve seat; and a diaphragm configured to communicate with and interrupt the second inflow passage and the outflow passage. An end portion of the second inflow passage is open to the valve chamber. The valve seat is provided on a peripheral edge of a location where the valve chamber and the second inflow passage communicate with each other. The annular groove is open to the valve chamber and is formed around the second inflow passage. An end portion of the outflow passage is open to the annular groove. The first inflow passage has a plurality of flow passages including an inflow port and a plurality of outflow ports, and each outflow port is open to the annular groove.