To improve the operability, by receiving a cylinder speed and an operator's command signal and controlling the hydraulic cylinder to a required speed in response to the speed difference.

A joy stick position detector 220 detects the position of a joy stick control lever 219 and electrical actuation command signals showing the required speeds of respective hydraulic cylinders are transmitted to a controller 208. Cylinder speed detectors 216, 218 detect the speed of lift cylinders 106A, 106B and a tilt cylinder 114 and transmit respective speed signals. The controller 208 is provided with a software having a memory of a look-up table obtaining the magnitude of a specified electric bubble signal. The controller 208 receives operator's command signals and transmits electric bubble signals in response thereto. The bubble means 202 receives electric bubble signals and gives the hydraulic fluid flows to respective hydraulic cylinders in response thereto. In this way, the speed of working tools can be accurately controlled at a speed required by the operator.