A valve timing adjusting apparatus includes a housing, a vane rotor, and a spiral spring. The spiral spring has a most radially inward part engaged with a rotational shaft of the vane rotor in a state, where the most radially inward part is wound around the rotational shaft. The rotational phase has an intermediate position defined between a full retard position and a full advance position of the rotational phase. The spiral spring has a radially outward segment that is located radially outward of the most radially inward part. When the rotational phase is in a range on a retard side of the intermediate position or on an advance side of the intermediate position, the radially outward segment is engaged with the stopper such that the spiral spring urges the vane rotor in the advance direction or in the retard direction relative to the housing, respectively.