To control an electric current so stably in a transient area irrespective of any disturbance factor such as variations in supply voltage and solenoid resistance, etc., at the time of controlling the current value of a solenoid valve installed in an industrial vehicle, checking any shock in time of the starting of material handling equipment, and to maintain the good responsiveness of each individual equipment.

A central processing unit determines a duty output central value Dcent for defining the 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. This central processing unit compensates the last value Dcent with a compensation value made up by multiplying a difference I (=Iaim-Idet) between the desired current value Iaim and the current detected value Idet by a gain G, thereby determining this time value Dcent (S90). This gain G is defined that a reference gain determined in consideration of stability in a control system on the assumption that battery voltage is in reference voltage Vbase and solenoid resistance is in a resistance value at the time of roan temperature, is compensated according to the battery voltage detected value Vbatt (S80).