To provide a pressure reducing valve for setting the pressure reducing function of a pressure reducing valve validly or voidly by a simple operation.

This pressure reducing valve is provided with a valve unit 4 equipped with a partition 7 for dividing a primary pressure chamber 2 and a secondary pressure chamber 3, wherein the partition 7 is opened with a valve port 8 communicating with the primary pressure chamber and the secondary pressure chamber; a valve bar 9 formed inside the valve unit 4 so as to be displaced according to the pressure of the secondary pressure chamber 3; and a valve body 5 supported by the valve bar 9 for opening/closing a valve port 8. The valve bar 9 is provided with a control means 30 equipped with an extended axial part 31 protruded to the outside of the valve unit 4 according to the movement of the valve body 5 to the valve opening direction, and configured to control the displacement of the valve bar 9 to the valve closing direction by holding an extended shaft part 31 protruded to the outside of the valve unit 4 in a valve opening state.