To simplify a circuit (hardware) required in the light of feedback control over the. current value of a solenoid valve, and to secure its relatively high responsiveness, in an industrial vehicle.

A central processing unit performs a compensation process compensating a duty output value Dout to determine a duty value (%) of a pulse width modulation signal to be inputted into a transistor interposed between a battery and a solenoid valve, on the basis of program data. The central processing unit calculates a difference ΔI(=Iaim-Idet) between the current desired current value Iaim and the current detected value Idet (S20), and a compensation value (G.ΔI) is added to the last duty output value Dout and thereby the current duty output value Dout is calculated (S30). A constant G is of gain determined in due consideration of the safety of a control system from a transfer function in this integral type control system.