To provide an over current protection circuit for a voltage regulator, which accurately detects an over current.

Even when drain currents of an output transistor 10 and an NMOS 54 are instantaneously shut off, NMOSs 54, 55 are not driven in a shut-off region, but continuously driven in a linear region or a saturation area by a resistor R1, so that the NMOSs 54, 55 may not be restored to the linear region or the saturation region after being shifted to the cut-off region. Since the over current protection circuit 50 can be driven at a high speed, an over current can be more accurately detected.