PURPOSE: To secure safe and positive braking force in the landing gear of an aircraft or the like by detecting each braking force applied to many wheels by a braking torque sensor compact and easy to fit/remove.

CONSTITUTION: A wheel bearing part 3 for bearing the axle 2 of a wheel 1 is provided with a flange 11 for mounting a brake 10 disposed being enclosed in the wheel 1, and the brake 10 is mounted through a strain gage sensor device formed of a ring member 12 with a strain gage sensor 12 fixed to the circumferential bottom part of U-shape cross section by epoxy resin. The distortion of the ring member 12 generated by braking is detected to compute the present braking torque quantity from the correlation between the previously obtained distortion quantity and braking torque quantity, and the control quantity of an actuator is changed accordingly to control in such a way as to obtain the specified braking torque.