An electric power steering device of a steer-by-wire type, comprising: a steering input mechanism, which includes a steering wheel to be operated by a driver; a reaction force motor, which is configured to apply a steering reaction force to the steering wheel; a steering motor, which is configured to output a steering force; a steering mechanism, which cannot be mechanically connected to the steering input mechanism, and is configured to steer a steered wheel through the steering force generated by the steering motor; and a drive control device, which is configured to carry out drive control for the steering motor and the reaction force motor, characterized in that at least the reaction force motor is constructed of a double-winding motor of a double-inverter type in which each of two windings is individually driven by one of the two inverters, wherein, when the double-winding motor of the double-inverter type fails, the drive control device is configured to control, in accordance with a drive current detected in a failed system out of two systems of the windings of the double-winding motor, a drive current to a winding of the failed system and to a winding of a non-failed system, or, in a case where another motor is provided together, a winding of the another motor provided together, wherein the drive current to the winding of the non-failed system, or to the winding of the another motor provided together, is increased by an amount for supplementing the decreased output of the failed system, wherein the double-winding motor (7,12) of the double-inverter type comprises a three-phase double-winding motor of the double-inverter type including two sets of three-phase windings (19,20) and two inverters (210a,210b) configured to individually drive the respective two sets of the three-phase windings. a steering input mechanism, which includes a steering wheel to be operated by a driver; a reaction force motor, which is configured to apply a steering reaction force to the steering wheel; a steering motor, which is configured to output a steering force; a steering mechanism, which cannot be mechanically connected to the steering input mechanism, and is configured to steer a steered wheel through the steering force generated by the steering motor; and a drive control device, which is configured to carry out drive control for the steering motor and the reaction force motor, characterized in that at least the reaction force motor is constructed of a double-winding motor of a double-inverter type in which each of two windings is individually driven by one of the two inverters, wherein, when the double-winding motor of the double-inverter type fails, the drive control device is configured to control, in accordance with a drive current detected in a failed system out of two systems of the windings of the double-winding motor, a drive current to a winding of the failed system and to a winding of a non-failed system, or, in a case where another motor is provided together, a winding of the another motor provided together, wherein the drive current to the winding of the non-failed system, or to the winding of the another motor provided together, is increased by an amount for supplementing the decreased output of the failed system, wherein the double-winding motor (7,12) of the double-inverter type comprises a three-phase double-winding motor of the double-inverter type including two sets of three-phase windings (19,20) and two inverters (210a,210b) configured to individually drive the respective two sets of the three-phase windings.