A supply valve for supplying air to a wearer of an air respirator is attached to a facepiece and includes an inflow port for medium-pressure air (S1), a supply port for the medium-pressure air (S1) with respect to the facepiece, and a diaphragm. The supply valve includes a cylindrical housing and a slider that is reciprocally slidable on the inner peripheral surface of the housing in an axial direction thereof. The housing includes a pilot valve seat urged toward a pilot valve on an outer side of the one end portion in the axial direction and a main valve seat on an inner side of an opposite end portion in the axial direction. The inflow port is formed between the one end portion and the opposite end portion. The slider includes the pilot valve contactable with the pilot valve seat and a main valve urged toward the main valve seat.