A motor for an electric power steering device, includes: a housing side bearing which is placed on the output side of a shaft of a rotor placed in a frame, and is supported by a housing connected to the frame; and a frame side bearing which is placed on the opposite output side of the shaft of the rotor, and is composed of an outer ring and an inner ring supported by the frame. The motor is controlled by an electronic control unit which is coaxially placed with the rotor, the motor including: a bearing box which supports the frame side bearing, and is formed with a closed end section between the closed end section and the side of the frame side bearing; an axial elastic body which is placed on the closed end section of the bearing box, and applies a preload in an axial direction to the outer ring of the frame side bearing; and a radial elastic body which is placed on the outer circumferential side of the outer ring of the frame side bearing, and applies a preload in a direction perpendicular to the axial direction.