In an electrically driven power steering device of the present invention, the abnormality detection ability is improved and the erroneous detection of the abnormality is suppressed. A current sensor (59) disposed at an upstream side or alternatively at a downstream side of an inverter (54) detects a direct current bus bar current, and a phase current detecting section (60) detects or estimates current values, i.e., Iu, Iv, Iw of the respective phases of a motor on a basis of the direct current bus bar current and PWM duty signals. And an estimated primary current calculating section (56) calculates an estimated primary current, i.e., (Iu*Du+Iv*Dv+Iw*Dw)/100%, in an abnormality monitoring section (57), the abnormality of the control unit is monitored on the basis of the direct current bus bar current and the estimated primary current.