PURPOSE: To reduce a shock generated due to the stroke end of a hydraulic cylinder, by detecting the length of the cylinder being expanded/contracted, and reducing the speed at which the hydraulic cylinder expands and contracts when the length has reached a dangerous zone near the stroke end.

CONSTITUTION: A detector 14 detects the length l of a hydraulic cylinder 5 and inputs this detected signal to a controller 15; the controller 15 then determines whether or not the length l is more than the length le which is preset by a length setting device 15 and which has its end located near the end of its stroke; when it is, the controller reduces the rotating speed N of an engine 11 to reduce the speed at which the hydraulic cylinder 5 expands and contracts. The shock generated due to the stroke end of the cylinder can be reduced while efficient strokes are sufficiently secured.