This seatbelt apparatus of a vehicle is provided with: a seatbelt; a belt reel on which the seatbelt is wound; a motor that drives a rotation of the belt reel; a controller that controls a driving amount of the motor; a winding position detection device that detects a winding position of the belt reel. The controller performs a first control mode in which a substantially constant electricity is supplied to the motor, and a second control mode in which the electricity supplied to the motor is controlled based on a predetermined rule; and sets an initial value for the second control mode based on changes in the winding position detected by the winding position detection device, while changing from the first control mode to the second control mode.