A control device controls a torque transmission device. The torque transmission device includes an actuator that operates by being energized and a torque transmission portion that is switched to a transmission state or a non-transmission state by the actuator operating, and transmits a torque between a first transmission portion and a second transmission portion when the torque transmission portion is in the transmission state. The control device includes a target calculation unit, a mode determination unit, and a control unit. The target calculation unit calculates a target transmission torque that is a torque to be transmitted between the first transmission portion and the second transmission portion. The mode determination unit determines an operating mode among an engagement mode, a release mode, and a steady mode. The control unit controls the actuator based on the operating mode determined by the mode determination unit.