Seat belt retractor for a vehicle and method for protecting passengers

A seat belt retractor (50) for a vehicle may include a motor (51) which is operated in response to a control signal of a seat belt controller (61), a reduction gear (52) which transmits a rotational force of the motor (51), and a rotary roller (53), which is rotated by a rotational force transmitted from the reduction gear (52), one end of a safety belt (20) to the rotary roller (53) is coupled.