A valve timing adjusting apparatus includes a first rotor, a second rotor, and a bias mechanism. The bias mechanism is provided to one of the first and second rotors. The bias mechanism includes a resilient member and a projection portion that is rotatable together with the one of the first and second rotors. The projection portion is rotatable relative to the other one of the rotors and contacts a contact part of the other one. Restoring force of the resilient member is applied to the other one of the first and second rotors through the projection portion. The contact part includes an inclination portion that is configured to increase and decrease restoring force of the resilient member.