A control device controls a collision mitigation operation of a collision mitigation device applied to a vehicle. The control device includes: a determination unit that determines the probability of a collision between the vehicle and an object on the basis of the position of the object detected by a detection device and a history of positions of the object; an execution unit that causes the collision mitigation device to execute the collision mitigation operation in response to determining that the probability of a collision is higher than a predetermined value; and a condition changing unit that executes, in response to determining that the detected object is a pedestrian or bicycle emerging rapidly from behind a stationary object, a condition changing process for making a change such that the determination unit determines the probability of a collision without using the history of positions of the object.