A rotary electric device control device controls driving of a rotary electric device including a plurality of winding sets. The rotary electric device control device includes: a plurality of drive circuits; and a plurality of control units. The control units include signal output units for outputting control signals to the drive circuits corresponding to the control units, respectively, and communicate with each other. The control units include: one master control unit; and at least one slave control unit. An electric power steering device includes: a rotary electric device control device; the rotary electric device that outputs an assist torque for assisting a steering operation of a steering wheel by a driver; and a power transmission unit that transmits a driving force of the rotary electric device to a drive target.