A seatbelt apparatus includes a first pretensioner for winding a webbing to a retractor by a predetermined tension, a second pretensioner for applying a tension to the webbing in an emergency to restrain a passenger finally, a brake-pedal stroke sensor for detecting a manipulated amount of a brake pedal, a laser radar for detecting an obstacle in front of a vehicle and a first controller for controlling the tension by the first pretensioner in accordance with at least one of a tension control based on the detection data by the brake-pedal stroke sensor and another tension control based on the detection data by the laser radar. In operation, under the tension control based on detection data by the brake-pedal stroke sensor, the first controller allows the first pretensioner to always operate when it is judged that the vehicle is braking in an emergency. Under the tension control based on detection data by the laser radar, the first controller allows the first pretensioner to operate selectively.