A control device for a vehicle seat belt, comprising: a retraction unit that is configured to retract a seat belt through use of a driving force of a motor and to stop retracting the seat belt when the motor is stopped from being driven; an acceleration measurement unit that is configured to measure an acceleration of a vehicle in a vehicle longitudinal direction; a state detection unit that is configured to detect whether or not the vehicle is in a stable state while running; a vehicle speed sensor that is configured to measure a speed of the vehicle; a steering angle sensor that is configured to measure a steering angle of the vehicle; and a control unit that is configured to stop driving the motor when the acceleration measured by the acceleration measurement unit during driving of the motor has remained lower than a first set acceleration for at least a first set time and the vehicle has remained in the stable state detected by the state detection unit for at least a second set time, and to continue to drive the motor at least either when the acceleration has remained lower than the first set acceleration for a time shorter than the first set time, or when the vehicle has remained in the stable state detected by the state detection unit for a time shorter than the second set time; wherein the state detection unit is configured to detect a running state of the vehicle as the stable state when an estimated acceleration (Ac) obtained based on the speed and the steering angle is equal to or lower than a second set acceleration (Ak), and to detect the running state of the vehicle as an unstable state when the estimated acceleration is higher than the second set acceleration. a retraction unit that is configured to retract a seat belt through use of a driving force of a motor and to stop retracting the seat belt when the motor is stopped from being driven; an acceleration measurement unit that is configured to measure an acceleration of a vehicle in a vehicle longitudinal direction; a state detection unit that is configured to detect whether or not the vehicle is in a stable state while running; a vehicle speed sensor that is configured to measure a speed of the vehicle; a steering angle sensor that is configured to measure a steering angle of the vehicle; and a control unit that is configured to stop driving the motor when the acceleration measured by the acceleration measurement unit during driving of the motor has remained lower than a first set acceleration for at least a first set time and the vehicle has remained in the stable state detected by the state detection unit for at least a second set time, and to continue to drive the motor at least either when the acceleration has remained lower than the first set acceleration for a time shorter than the first set time, or when the vehicle has remained in the stable state detected by the state detection unit for a time shorter than the second set time; to stop driving the motor when the acceleration measured by the acceleration measurement unit during driving of the motor has remained lower than a first set acceleration for at least a first set time and the vehicle has remained in the stable state detected by the state detection unit for at least a second set time, and to continue to drive the motor at least either when the acceleration has remained lower than the first set acceleration for a time shorter than the first set time, or when the vehicle has remained in the stable state detected by the state detection unit for a time shorter than the second set time; wherein the state detection unit is configured to detect a running state of the vehicle as the stable state when an estimated acceleration (Ac) obtained based on the speed and the steering angle is equal to or lower than a second set acceleration (Ak), and to detect the running state of the vehicle as an unstable state when the estimated acceleration is higher than the second set acceleration.