A brake system includes a front and a rear wheel brake circuit which are independent of each other. Each circuit includes: a master cylinder connected to a brake caliper through the main brake line; a hydraulic pressure modulator which causes an electrically-operated motor to generate hydraulic pressure; and a normally-open electromagnetic on-off valve. When the two brake circuits are moved in response to operation of a braking operation unit in one circuit, in the brake circuit for which a braking operation unit was operated earlier, the electromagnetic on-off valve opens so that the brake caliper is operated by use of hydraulic pressure from the master cylinder. In the other brake circuit, the electromagnetic on-off valve is closed so that the brake caliper is operated by use of hydraulic pressure from the hydraulic pressure modulator. The braking system uses simple wheel braking mechanism and piping, and concurrently reduces electric current consumption.