To provide a valve timing adjusting device capable of securing high seal performance even when processing accuracy of an inner face of a housing is reduced.

This valve timing adjusting device is provided with the housing H rotating together with a rotation transmitting member 22 for transmitting rotation to a camshaft 17 and a vane rotor 40 provided inside the housing H, having a vane 44 relatively rotatable with respect to the housing H and rotating integrally with the camshaft 17. In accordance with pressure of working fluid supplied to a hydraulic chamber formed by the housing H and the vane 44 of the vane rotor 40, the camshaft 17 is controlled to an advance side or a retard side. An elastic seal member 80 is provided on the outer peripheral face and both end faces of the vane rotor 40, and is pressed against the inner face of the housing H.