IN-VEHICLE VENTILATION SYSTEM

An in-vehicle ventilation system includes a power window mechanism (11a, 11c, 11d) configured to open and close a window of a vehicle and a control unit configured to control the power window mechanism. The control unit (30) is further configured to acquire a first environmental information representing an environment inside the vehicle (i70) and a second environmental information representing an environment outside the vehicle (i40), automatically select, based on the first environmental information and the second environmental information, a specific ventilation adjustment mode suitable for at least one occupant of the vehicle out of a plurality of ventilation adjustment modes and control the power window mechanism according to the selected ventilation adjustment mode.