In a brake system for a motorcycle in which the operation of a pressure-regulating unit interposed between fluid pressure generator and a wheel brake is controlled by a control unit on the basis of a value detected by operating amount detector for detecting an operating amount of a brake operating element, to prevent the influence of vibrations transmitted from an engine from being exerted on the pressure-regulating unit. A support member for supporting the pressure-regulating unit is flexibly supported, though elastic members, by a pair of frame sections which are arranged on both the left and right sides of an engine body and by a crossmember which connects both the frame sections to each other on the rear side of the engine body so as to constitute a part of a body frame F together with the frame sections.