A robot calibrating apparatus calibrating a command value for a robot body 2 whose position and orientation is controlled based on the command value, includes an operating unit configured to calculate a calibrating function of calibrating the command value, based on the difference between an ideal position and orientation of the robot body 2 and an actual position and orientation of the robot body 2. The ideal position and orientation is operated based on a command value RHTcom for calibration used during calibration or on a control result value which is a result of control according to the command value. The actual position and orientation is operated based on a measurement value RHT′meas for calibration acquired by a camera 3 arranged at a prescribed relative position and orientation with respect to the robot body 2 during the robot body 2 being controlled according to the command value for calibration.