An inertial drive actuator includes a fixed member, a vibration substrate which is disposed on the fixed member, a displacement generating unit which causes a reciprocating movement of the vibration substrate with respect to the fixed member, a moving body which is disposed on the vibration substrate, and which is made of a magnetic body which moves with respect to the vibration substrate due to inertia with respect to the reciprocating movement of the vibration substrate, a coil which is provided on the moving body, and a driving unit which applies a voltage for causing a reciprocating movement of the moving body, and which controls a frictional force generated between the vibration substrate and the moving body by making an electromagnetic force act by applying an electric current to the coil.