A restraining device control system includes: a restraining device that is provided at a vehicle seat and that restrains an occupant seated in the vehicle seat; a surrounding environment detection unit that detects an environment surrounding a vehicle; and a control unit that increases a restraining force on the occupant by the restraining device in a case in which it has been predicted, from the surrounding environment of the vehicle, that vacillation of the vehicle while in an autonomous driving mode will exceed a threshold amount and that decreases the restraining force on the occupant by the restraining device in a case in which it has been predicted, from the surrounding environment of the vehicle, that the vehicle will maintain a state in which vacillation of the vehicle while in the autonomous driving mode is less than the threshold amount.