PURPOSE: To provide a brake device capable of interlocking so as to automatically increase single braking force following the increase of a steering angle, simplifying operation, and a small sharp turn in a brake device having single brake structure for braking a turn inner side rear wheel in steering.

CONSTITUTION: This brake device is provided with a braking means 13 for actuating a brake mechanism 12 to a rear wheel on a turn inner direction side when the steering angle of a front wheel exceeds a set value, and also is interlocked so as to increase braking force too by the braking mechanism 12 following the increase of the steering angle of the front wheel.