A device controls a defogging unit of a vehicle to be driven in a driving mode corresponding to a self-driving degree indicating a degree of depending on a self-driving system for a driving operation, and the defogging unit defogs a window of the vehicle. The device includes: an identification unit that identifies the self-driving degree; and a control execution unit that controls the anti-fogging function exhibited by the defogging unit. The self-driving degree is defined as exhibiting a higher value as the degree of depending on the self-driving system for the driving operation is larger. When the self-driving degree identified by the identification unit is a second value higher than a first value, the control execution unit controls the anti-fogging function executed by the defogging unit to be lower than that when the self-driving degree identified by the identification unit is the first value.