To secure valve opening of an injector, even in a state in which a battery voltage is lowered in a fuel injection device composed, so as to switch from a high electric current application to the low application on the way of vale opening of the injector.

When a battery voltage +B is lowered, ECU 200 prolongs the on time of a switching signal SG1 for a constant current value. Since the inductance of each of the solenoid coils 101a to 104a is reduced gradually with the lapse of time, the time required until the current reaches a first drive current value is lengthened. Accordingly, even though the time required for opening the valve is prolonged because the increase speed of the attracting force of solenoid is delayed, the predetermined time for which the first drive current value is applied is prolonged. Therefore, the valves of the injectors 101 to 104 can be opened surely.