Grille shutter device

A grille shutter device (10, 30) adapted to be arranged at a front portion of a vehicle body (2), the grille shutter device (10, 30) including a main air inlet (15, 35) taking air to flow the air to a specific heat exchanger (6) arranged in the vehicle body (2), a shutter mechanism (11,31) arranged at the main air inlet (15, 35), the shutter mechanism (11, 31) opening and closing to control a flow rate of the air flowing from the main air inlet (15, 35) to the specific heat exchanger (6), and a bypass air inlet (21, 41) allowing the air to bypass the shutter mechanism (11, 31) to guide the air to the specific heat exchanger (6).