A motorcycle brake system enables a smooth switching to a hydraulic loss simulator to provide an improved feeling of braking operation. A brake operating unit includes a brake caliper, an electromagnetic on-off valve (V1) which blocks a main brake passage, a pressure sensor, a hydraulic modulator, and a hydraulic loss simulator. The brake system allocates a braking force to front and rear wheels by controlling the hydraulic modulator based on a result of detection by the pressure sensor. The brake operating unit has a brake light switch for detecting the starting of operation thereof, actuates an electromagnetic on-off valve (V1) to block the main brake passage based on a result of detection by the brake light switch, and unblocks the main brake passage when a predetermined amount of time elapses without any input made to the pressure sensor in a standby state with the main brake passage blocked.