Valve timing control unit

A valve timing control unit comprising:

• at least one valve timing control mechanism including:
• a driving rotary body configured to rotate in synchronization with a crankshaft of an internal combustion engine;
• a driven rotary body that is configured to rotate integrally with a camshaft that opens and closes a valve of a combustion chamber of the internal combustion engine, that is coaxial with a rotation axis of the driving rotary body, and that is disposed so that a relative rotational phase thereof relative to the driving rotary body is changeable with use of a bearing;
• an electric motor and a deceleration gear each configured to set the relative rotational phase;
• and
• a phase sensor unit configured to detect the relative rotational phase of the driving rotary body and the driven rotary body as an actual phase with respect to the rotation axis as a center;
• and
• a controller configured to control the electric motor to reduce a phase difference between the actual phase detected by the phase sensor unit and a target phase,
• wherein the controller includes a swing controller configured to swing the target phase in vicinity of the target phase in response to (i) the target phase being maintained and (ii) the actual phase having a fluctuation amount held in a holding region, in which the fluctuation amount is less than a preset value relative to the target phase.