A rotary connector device is provided for restraining an error of rotational transmission between a steering wheel and a steering-angle sensor and restricting an increase of a steering-wheel detection error, making it possible to perform timely vehicle control. The rotary connector has: a body which is supported at a combination switch side and is adapted to pass a steering shaft; a rotor adapted to pass the steering shaft; and an attachment adapted to rotatably couple the rotor to the body and conjunctively rotate relative to the rotor, sensor-engagement recessed portions engaging with a steering-angle sensor to transmit a rotation, the recessed portions being provided at the attachment, wherein wheel-engagement protrusions engaging with a steering wheel are provided at the attachment.