Provided is a buckle device that fixes a seat belt mounted on a 2nd-row seat or a 3rd-row seat to the vehicle body floor in a vehicle. The buckle device may include a buckle bracket having an upper end with a hole for connecting with a seat belt and a lower end connected to a rail on a vehicle body floor by a buckle connection bolt, and a wire fixing bracket connected between a side of the buckle bracket and a side of a seat frame and absorbing vibration of a seat.