A force detector provided between a robot arm and a robot hand detects forces Fx, Fy, and Fz. A robot controller performs a filtering process for the forces Fx and Fy by a first low-pass filter of a cutoff frequency Fc1, moves the robot hand so that the forces Fx and Fy become smaller, corrects a trajectory of the robot arm, performs a filtering process for the force Fz by a second low-pass filter of a cutoff frequency Fc2 having a frequency higher than the cutoff frequency Fc1, performs a threshold value determination for the force Fz, and stops the movement of the robot hand when the force Fz exceeds a threshold value during a fitting operation.