A grill shutter unit comprises a shutter unit provided in back of a traveling-air introductory port formed at a front end of a vehicle body and including shutter members, and a traveling-air guide member including a guide frame portion provided at an outer peripheral edge portion of the shutter unit and a seal portion provided to extend forward continuously from a front end of the guide frame portion and be made from soft synthetic resin having more flexibility than the frame portion, wherein the grill shutter unit is configured such that when the shutter members are closed, a seal portion of the traveling-air guide member is pressed against an outer peripheral wall face of the traveling-air introductory port by pressure of traveling air shut off by the shutter members closed.