To provide a brake device for an automatic traveling carriage capable of remarkably reducing battery consumption.

The braking device is equipped with: a frictional block 13 for pressurizing an outer peripheral face of a wheel 3; a motor M3 composed capable of rotating an output shaft 14 by 180° in the normal and reverse directions; and an operational force transmission mechanism 15 for pivotably supporting and connecting the motor output shaft 14 to the frictional block 13, moving the frictional block 13 by normal rotation of the output shaft 14 to a braking position in which the frictional block 13 is pressurized to the outer peripheral face of the wheel 3, and moving the frictional block 13 to a brake releasing position by reverse rotation of the motor output shaft 14 away from the outer peripheral face of the wheel 3. The brake device is structured so that when the frictional block 13 is at the braking position, the motor output shaft 14, the operational force transmission means 15, the frictional block 13, and an axle 3a are positioned on a straight line, the braking state is mechanically locked, and feeding of power to the motor M3 is cut off when the frictional block 13 comes to the braking position and the brake releasing position.