To efficiently reduce the pulsation of the discharged liquid generated by a return pump by forming a plug of the elastic material in a damper chamber structure in which an opening end of a recessed part for the damper chamber formed in a housing is covered by the plug.

If a wheel is locked in applying a brake by stepping in a brake pedal 1, an inlet valve 5 is closed, an outlet valve 8 is opened, and the working fluid in a wheel cylinder 3 flows into a reservoir 6 through a return passage 7. The hydraulic pressure in the wheel cylinder 3 is controlled to avoid locking of the wheels. The working fluid in the reservoir 6 is dipped by a return pump 9 and returned to a master cylinder side 2 through a damper chamber 12. A plug to cover the damper chamber 12 is formed of the synthetic resin material. The pulsation of the working fluid is reduced by elastically deforming the plug, especially a bottom part according to the pulsation.