A fitting apparatus includes a robot arm having, at the forward end thereof, a gripper for holding a workpiece, a force detector for detecting a force and moment received by the workpiece held by the gripper, and a controller for controlling an operation of the robot arm. The controller includes a motion command generating unit for generating an operation command to fit two workpieces to each other, and an operation command correcting unit for correcting the operation command so as to correct the position of the gripper in a direction perpendicular to the fitting direction and the orientation of the gripper around an axis perpendicular to the fitting direction until the detected force and moment become less than or equal to a threshold value, based on either maximum values of the force and moment detected by the force detector while the two workpieces are in contact with each other or the force and moment detected by the force detector when the two workpieces first come into contact with each other.