1. An image processing apparatus comprising: a communication device capable of performing data communication with a robot controller that controls a motion of a robot; an imaging device that captures an image of a target being an operation target of the robot; a command transmitting unit for transmitting to the robot controller a movement command to move an end effector to a plurality of predetermined positions so as to change a relative position of the target, which becomes an imaging target, with respect to the imaging device; a movement coordinate acquiring unit for acquiring first coordinate values being each of position coordinates of the end effector having moved in accordance with the movement command; an imaging controlling unit for controlling an operation of the imaging device so as to capture an image of the target at each movement destination, to which the end effector has moved; an image detecting unit for detecting second coordinate values being position coordinates of the target based on the image of the target captured at each movement destination; and a calibration executing unit for calculating a conversion rule between both of the coordinates based on the plurality of acquired first coordinate values and the plurality of detected second coordinate values.