To achieve simple and highly responsive motion control of a fluid pressure controlled actuator.

A difference between a target position and a current position of a piston 13 is acquired to obtain proportionally controlled pressure that is proportional to the difference, variable offset pressure based on a derivative of the difference, and constant base offset pressure. Of the two chambers 11, 12 separated by the piston 13 in a cylinder 10, one on the thrust side is set at fluid pressure obtained by adding the proportionally controlled pressure to offset pressure which is the base offset pressure plus or minus variable offset pressure. The chamber on the anti-thrust side is set at offset pressure which is the base offset pressure plus or minus variable offset pressure.