PURPOSE: To improve flexibility by providing a reference point in an action area to also prepare a reference pattern of previously measuring an action error, measuring an error from the reference point by a reference point measuring sensor of a robot, and obtaining an error amount successively from a high order of the reference pattern so as to perform action correction.

CONSTITUTION: When a fine error of the same value is given by a parameter which is a primary factor of absolute position error in a robot 1, an error order is provided in the order of large influence given to a robot arm point end position error. Next in a controller 4, a sensor 3 is used to obtain an error amount, between theoretical and actual positions, decreased by calculating by error correction the error primary factor of the largest error sensitivity. Similarly, successively in accordance with a order of the error sensitivity, the rest of error primary factor is calculated to decrease the error.