A cartridge vane pump configured to be accommodated in a body in an attachable and detachable manner, the cartridge vane pump comprising: a rotor linked to a driving shaft, the rotor being configured to be rotationally driven; a plurality of vanes provided in the rotor so as to be able to reciprocate in a radial direction of the rotor; a cam ring having an inner circumference cam face with which the plurality of vanes are brought into sliding contact; a plurality of pump chambers defined in the cam ring by an outer circumferential surface of the rotor, the inner circumference surface of the cam ring, and the adjacent vanes, a side member brought into contact with first end surfaces of the rotor and the cam ring; a cover member brought into contact with second end surfaces of the rotor and the cam ring, the cover member being configured to be attached to the body; and a sealing member provided in an outer circumference of the side member, the sealing member being configured to seal a gap between the outer circumference of the side member and an inner circumference of the body, a first restricting portion configured to restrict movement of the sealing member towards the rotor side; a second restricting portion configured to restrict movement of the sealing member towards an opposite side from the rotor; and an accommodating space defined by the first restricting portion and the second restricting portion, the sealing member being configured to be accommodated in the accommodating space, and wherein the first restricting portion is formed to have an outer diameter larger than an outer diameter of the second restricting portion so as to be able to compress the sealing member with the body in an axial direction of the driving shaft, characterized in that: the side member further has a suction port for guiding the working fluid into the pump chambers, the suction port being formed so as to form cut-out shapes that open at an end surface of the side member facing the cam ring and at an outer circumferential surface of the side member. a rotor linked to a driving shaft, the rotor being configured to be rotationally driven; a plurality of vanes provided in the rotor so as to be able to reciprocate in a radial direction of the rotor; a cam ring having an inner circumference cam face with which the plurality of vanes are brought into sliding contact; a plurality of pump chambers defined in the cam ring by an outer circumferential surface of the rotor, the inner circumference surface of the cam ring, and the adjacent vanes, a side member brought into contact with first end surfaces of the rotor and the cam ring; a cover member brought into contact with second end surfaces of the rotor and the cam ring, the cover member being configured to be attached to the body; and a sealing member provided in an outer circumference of the side member, the sealing member being configured to seal a gap between the outer circumference of the side member and an inner circumference of the body, a first restricting portion configured to restrict movement of the sealing member towards the rotor side; a second restricting portion configured to restrict movement of the sealing member towards an opposite side from the rotor; and an accommodating space defined by the first restricting portion and the second restricting portion, the sealing member being configured to be accommodated in the accommodating space, and wherein the first restricting portion is formed to have an outer diameter larger than an outer diameter of the second restricting portion so as to be able to compress the sealing member with the body in an axial direction of the driving shaft, characterized in that: the side member further has a suction port for guiding the working fluid into the pump chambers, the suction port being formed so as to form cut-out shapes that open at an end surface of the side member facing the cam ring and at an outer circumferential surface of the side member.