To maintain a degree of performances of construction machines even under an abnormal condition of CPUs.

An intermittent signal B of current-direction values, from a multiplexer 2 to represent a direction value to a proportional solenoid valve 8, turns into a continuous signal C of current-direction values by a stick circuit 4 formed of capacitors. An integrating circuit 13 comparatively integrates the signal C of current-direction values and a signal G of actual current values that presents a drive current F of the proportional solenoid valve 8, and then generates a signal D of amended current values in order to operate the comparative solenoid valve 8 by the direction values of the signal B of current-direction values; in a case where there exists an abnormal charge in the capacitors of the stick circuit 4 due to leak current from the integrating circuit 13 when no signal B of current-direction values is supplied, the signal D of amended current values is caused correspondingly to the direction value depending on a signal I of basis-direction value from a circuit 14 to generate a basis-direction value, consequently, performance of construction machines is maintained to some extent.