The disclosed seat belt retractor and seat belt apparatus may comprise: an electric motor; a spool that is capable of winding and unwinding a seat belt for occupant restraint in association with the driving of the electric motor; and a controller for controlling the electric motor. A starting condition can be defined by the state of the seat belt relative to a vehicle occupant and the state of a vehicle door corresponding to the seat belt and, in cases where a starting condition is satisfied, the controller can be configured to control the electric motor to rotate in the belt winding direction such that the motor output of the electric motor is varied according to a satisfaction pattern of the starting condition.