To solve the problem that, when hydraulic actuators 4, 7 are driven by outputting operation signals to control valves 10, 11 from a controller corresponding to operation command signals from operation devices 16, 17, it takes long to raise pressure to pilot pressure set in counter-balance valves 12, 13 equipped with the hydraulic actuators 4, 7, thus causing the delay of operation, and to provide a control unit of a work machine having no delay of operation.

In the control unit of the work machine, when operation command signals from the operating units 16 and 17 are set to be sent to the operational direction wherein the counter balance valves 12 and 13 are actuated, the controller 30 outputs an operating signal with an amount of an operating signal larger than that of the operation command signals to control valves 10 and 11 during a designated time set in advance by receiving from the operating units 16 and 17, and then outputs the control signal in response to the operation command signal from the operating units 16 and 17 to the control valves 10 and 11.