A variable oil pump comprising: a pump housing ; an oil pump rotor housed in the pump housing and rotationally driven; an adjustment member housed in the pump housing and that adjusts an amount of oil discharged from the oil pump rotor by being displaced under hydraulic pressure supplied to a hydraulic chamber (U) between the pump housing and the oil pump rotor in a state where the oil pump rotor is rotatably held from an outer peripheral side; a seal member disposed in a portion where the adjustment member and the pump housing face each other and that seals oil leakage to an outside of the hydraulic chamber (U); a seal member holding portion provided in the adjustment member and that holds the seal member ; and an oil passage provided in the adjustment member and through which the hydraulic pressure in the hydraulic chamber (U) is drawn into the seal member holding portion , wherein the seal member holding portion includes a foreign matter storage portion formed in a vicinity of the root of the seal member and that stores foreign matter contained in the oil drawn from the hydraulic chamber (U) and that flows through the oil passage , characterized in that the foreign matter storage portion is formed in the seal member holding portion so as to extend in a thickness direction of the seal member perpendicular to a direction in which the oil passage extends, and a sectional area (S2) of the foreign matter storage portion in a direction perpendicular to a direction in which the foreign matter storage portion extends is larger than a sectional area (S1) of the oil passage in a direction perpendicular to the direction in which the oil passage extends. a pump housing ; an oil pump rotor housed in the pump housing and rotationally driven; an adjustment member housed in the pump housing and that adjusts an amount of oil discharged from the oil pump rotor by being displaced under hydraulic pressure supplied to a hydraulic chamber (U) between the pump housing and the oil pump rotor in a state where the oil pump rotor is rotatably held from an outer peripheral side; a seal member disposed in a portion where the adjustment member and the pump housing face each other and that seals oil leakage to an outside of the hydraulic chamber (U); a seal member holding portion provided in the adjustment member and that holds the seal member ; and an oil passage provided in the adjustment member and through which the hydraulic pressure in the hydraulic chamber (U) is drawn into the seal member holding portion , wherein the seal member holding portion includes a foreign matter storage portion formed in a vicinity of the root of the seal member and that stores foreign matter contained in the oil drawn from the hydraulic chamber (U) and that flows through the oil passage , characterized in that the foreign matter storage portion is formed in the seal member holding portion so as to extend in a thickness direction of the seal member perpendicular to a direction in which the oil passage extends, and a sectional area (S2) of the foreign matter storage portion in a direction perpendicular to a direction in which the foreign matter storage portion extends is larger than a sectional area (S1) of the oil passage in a direction perpendicular to the direction in which the oil passage extends. <EOS>