The seat belt device includes a first unit, a second unit, seat belt webbing, a spindle, a first pretensioner, a second pretensioner, and a controller. The first unit determines a possible collision of an automobile in response to a manipulation of the automobile by a driver. The second unit detects the collision of the automobile. The first pretensioner has a motor to rotate in response to a signal indicative of the possible collision determined by the first unit. The second pretensioner is pyrotechnically driven to rotate in response to a signal indicative of the collision detected by the second unit. The controller is configured to cancel an operation of the first pretensioner after an activation of the second pretensioner. The first pretensioner includes a limiter for restricting the motor from transmitting a driving force to the spindle exceeding a predetermined threshold.