To provide an electric power steering device capable of suppressing vibrations and noise of an electric motor, even though increasing of processing amount of a micro computer is slight.

The electric power steering device is provided with a torque sensor detecting steering toque added on a steering member (not shown), and the electric motor for assisting steering. A plurality of PWM signals S(0) to S(3) are produced every predetermined period, and current by the produced PWM signals S(0) to S(3) is made to flow, thereby driving the electric motor. A means calculating the pulse width of a part S(0), S(1) of the plurality of PWM signals S(0) to S(3) every period by interpolation on the basis of the pulse width of the remaining PWM signals S(2), S(3) and the pulse width of the remaining the PWM signals S(2), S(3) of a last period, is provided. A part of the PWM signals S(0), S(1) is produced by the calculated pulse width.

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