A hydraulic brake system including: (a) a first hydraulic-pressure generating device including a manual hydraulic pressure source; (b) a second hydraulic-pressure generating device including a power hydraulic pressure source; (c) a manual-operation-associated brake line including a communicating device that is to be brought into communication with the manual hydraulic pressure source and brake cylinder or cylinders of the plurality of hydraulic brakes; (d) an output hydraulic-pressure control device and a flow restraining device disposed in parallel with each other between the manual-operation-associated brake line and the second hydraulic-pressure generating device; and (e) a power hydraulic pressure source control device for activating the power hydraulic pressure source such that the hydraulic pressure is supplied to the manual-operation-associated brake line via the flow restraining device, when the output hydraulic-pressure control device cannot control the hydraulic pressure outputted by the second hydraulic-pressure generating device.