Disclosed is an electric power steering device that is able to retain the merits of a motor housing-equipped system and a gear box-equipped system while solving previously unsolved issues. The electric power steering device is equipped with a steering column (3) in which a steering shaft (2) that transmits a steering torque has been installed, an electric motor (12) that transmits steering assist force to the aforementioned steering shaft (2) via a gear mechanism within a gear box (11), and a control device that controls the drive of said electric motor (12). The aforementioned control device is provided with at least a drive circuit module (60) that has a switching element for driving the aforementioned electric motor and is equipped in the housing of said electric motor, and a control module (40) that controls the aforementioned drive circuit module (60) and is equipped in the aforementioned gear box.