A variable displacement pump includes: a pump body; a rotor; a cam ring; inlet and outlet ports; first and second fluid pressure chambers; a metering orifice provided in a discharge passage connected with the outlet port; a pressure regulating section arranged to regulate the pressure introduced into the first or second fluid pressure chamber, and including a high pressure chamber, a middle pressure chamber, and a low pressure chamber; a relief valve; a pilot orifice provided in a passage connecting the metering orifice and the middle pressure chamber, and having a circular section with a diameter of a mm; and a damper orifice provided in a passage connecting the outlet port and the high pressure chamber, and having a circular section with a diameter of b mm. The pilot orifice and the damper orifice satisfy the following relationships: a+2b−2.1≧0, −4a+b−16.3≦0, and a≦1.8.