A valve opening and closing timing control apparatus (1) includes: a driving side rotator (A) disposed rotatably about a rotation axis (X) and configured to rotate synchronously with a crankshaft (2); a driven side rotator (B) disposed rotatably about the rotation axis and configured to be rotatable relative to the driving side rotator and to rotate integrally with a valve opening/closing camshaft (3); a phase adjustment mechanism (C) configured to set a relative rotation phase between the driving side and driven side rotators by a driving force of an electric actuator (M), a biasing member (25) provided on an outer periphery of a drive shaft to apply a biasing force in a direction such that an inner gear is engaged with a ring gear; and a displacement regulation portion (R) configured to regulate a displacement of the inner gear.