A vane pump has an upper casing, a lower casing, a rotor and a motor. First to fourth points are defined on an outer peripheral end of a lower flat surface of the lower casing. The first point is farthest from an intersection between an axis of a shaft of the motor and the lower flat surface. A suction passage passing through the third point and a discharge passage passing through the second point are formed between the upper casing and the lower casing. The fourth point is defined in a range from the third point to the first point. The lower flat surface is provided to incline with respect to the axis of the shaft of the motor such that the fourth point is farthest from a motor case of the motor among points on the outer peripheral end.