This controller acquires the roll angle and pitch angle of a vehicle body detected by a body sensor. The controller acquires the roll angle of a work machine detected by a working machine sensor. The controller calculates a yaw angle error of the body sensor with respect to the body on the basis of the difference between the roll angle of the body and the roll angle of the work machine, and the pitch angle of the body. The controller calibrates the body sensor using the yaw angle error of the body sensor.