To provide an electric power steering control system that prevents an assist motor 11 from rotating in a direction opposite to a steering direction by a driver even if a current is supplied to the assist motor 11 in a direction opposite to the steering direction by the driver owing to electromagnetic noise or the like.

The electric power steering control system is equipped with: a motor driving circuit 3, which is composed by connecting a series circuit, composed by serially connecting MOS transistors U1, U2, and a series circuit, composed by serially connecting MOS transistors V1, V2, in parallel; and a drive command part 53 that outputs a drive command signal to the motor driving circuit 3 on the basis of steering torque information acquired from a torque sensor 12 detecting steering torque applied to a steering shaft. One ends of MOS transistors X1, X2 as cutoff switch means are connected to connection points J1, J2 between MOS transistors U1, U2 and MOS transistors V1, V2 so as to make the other ends of the MOS transistors X1, X2 output terminals for connecting the assist motor 11, respectively.