An electric power steering device, comprising: steering torque detection means for detecting a steering torque (tr) input from a steering wheel; a motor provided in a steering mechanism; a motor drive circuit comprising a switching element (Q1, Q2, Q3, Q4) for controlling energization of the motor; control amount calculation means for calculating a control amount (Im*, V*) of the motor based on the steering torque (tr) detected by the steering torque detection means; and switch control means for controlling the switching element (Q1, Q2, Q3, Q4) of the motor drive circuit in accordance with the control amount (Im*, V*) calculated by the control amount calculation means, thereby generating a steering assist torque from the motor; characterized in that the electric power steering device further comprises: internal resistance value measurement means (S20, S30) for energizing the motor so as not to rotate the steering wheel, thereby measuring an internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) of an energization path that is a circuit through which a current flows, including the motor drive circuit and the motor; semi-abnormal state detection means (S40, S42) for detecting a semi-abnormal state relating to an internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) of the energization path, in which the internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) measured by the internal resistance value measurement means (S20, S30) becomes a semi-abnormal value (≥ Rref_m1 and ≤ Rref_m2, ≥ Rref_q1 and ≤ Rref_q2) that exceeds a normal range (< Rref_m1, < Rref_q1) and is out of an abnormal range (> Rref_m2, > Rref_q2) in which the motor is intended to be stopped; and semi-abnormal occasion control amount limiting means (S41 to S46) for limiting, when the semi-abnormal state is detected, the control amount (Im*, V*) of the motor so that the energization of the motor for generating the steering assist torque is limited as compared to a case where the internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) falls within the normal range (< Rref_m1, < Rref_q1). steering torque detection means for detecting a steering torque (tr) input from a steering wheel; a motor provided in a steering mechanism; a motor drive circuit comprising a switching element (Q1, Q2, Q3, Q4) for controlling energization of the motor; control amount calculation means for calculating a control amount (Im*, V*) of the motor based on the steering torque (tr) detected by the steering torque detection means; and switch control means for controlling the switching element (Q1, Q2, Q3, Q4) of the motor drive circuit in accordance with the control amount (Im*, V*) calculated by the control amount calculation means, thereby generating a steering assist torque from the motor; characterized in that the electric power steering device further comprises: internal resistance value measurement means (S20, S30) for energizing the motor so as not to rotate the steering wheel, thereby measuring an internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) of an energization path that is a circuit through which a current flows, including the motor drive circuit and the motor; semi-abnormal state detection means (S40, S42) for detecting a semi-abnormal state relating to an internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) of the energization path, in which the internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) measured by the internal resistance value measurement means (S20, S30) becomes a semi-abnormal value (≥ Rref_m1 and ≤ Rref_m2, ≥ Rref_q1 and ≤ Rref_q2) that exceeds a normal range (< Rref_m1, < Rref_q1) and is out of an abnormal range (> Rref_m2, > Rref_q2) in which the motor is intended to be stopped; and semi-abnormal occasion control amount limiting means (S41 to S46) for limiting, when the semi-abnormal state is detected, the control amount (Im*, V*) of the motor so that the energization of the motor for generating the steering assist torque is limited as compared to a case where the internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) falls within the normal range (< Rref_m1, < Rref_q1). internal resistance value measurement means (S20, S30) for energizing the motor so as not to rotate the steering wheel, thereby measuring an internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) of an energization path that is a circuit through which a current flows, including the motor drive circuit and the motor; semi-abnormal state detection means (S40, S42) for detecting a semi-abnormal state relating to an internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) of the energization path, in which the internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) measured by the internal resistance value measurement means (S20, S30) becomes a semi-abnormal value (≥ Rref_m1 and ≤ Rref_m2, ≥ Rref_q1 and ≤ Rref_q2) that exceeds a normal range (< Rref_m1, < Rref_q1) and is out of an abnormal range (> Rref_m2, > Rref_q2) in which the motor is intended to be stopped; and semi-abnormal occasion control amount limiting means (S41 to S46) for limiting, when the semi-abnormal state is detected, the control amount (Im*, V*) of the motor so that the energization of the motor for generating the steering assist torque is limited as compared to a case where the internal resistance value (Rm, Rq1, Rq2, Rq3, Rq4) falls within the normal range (< Rref_m1, < Rref_q1).