To provide a controller of a linear solenoid which allows the improvement of the control responsiveness, without increasing the number of samplings of a detection signal.

A switching element TR, which turns a current path of a linear solenoid L on and off, is controlled by a PWM signal generated by a drive circuit 10. A microcomputer 16 fetches a detection signal, corresponding to a drive current for the linear solenoid L generated by a current detection circuit 12, via a smoothing circuit 14 and controls the duty ratio of the PWM signal, based on the detected value. The smoothing circuit 14 supplies a detection signal with no delay which corresponds to the drive current to the microcomputer 16 via a bypass B for a transient period, in which a target value for the drive current is changed and therefore the drive current is much changed. During the other period, it supplies a detection signal, having a stabilized signal level to the microcomputer 16 via an integration circuit consisting of a resistor R4 and a capacitor C.