To disuse a sealing member required to prevent the leakage of a brake fluid from a pump to the outside of a device.

The external wall surface of a cylinder 10 positioned on the opposite side to a suction port 8 with respect to a discharge port 9 is provided with a triangular groove 21 making a round in the radial direction of the cylinder 10. A pump 1 is inserted in a housing 2 from the suction port 8 side and further fitted into the triangular groove 21 while crushing a part of the housing 2 from the insert port side so as to fill the inside of the triangular groove 21 with a part of the housing 2. When the inside of the triangular groove 21 is filled with a part of the housing 2, a part of the housing 2 fitted into the triangular groove 21 loses the way back from the triangular groove 21. The bearing pressure of the pump 1 and housing 2 in the triangular groove 21 can therefore be made large so as to prevent the leakage of a brake fluid from a clearance between the pump 1 and housing 2.