In a brake system for a motorcycle in which the operation of a pressure-regulating unit interposed between fluid pressure-generating unit and a wheel brake so as to regulate an output fluid pressure of the fluid pressure-generating unit and to apply the regulated fluid pressure to the 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 arrange the fluid pressure-generating unit in a location which is close to the pressure control unit disposed on the rear side of an engine body and in which an installation space is easy to secure. The fluid pressure-generating unit, laid out in plan view between a left-right pair of seat rails which constitute a part of a body frame and which support a riders' seat, is supported by the seat rails.