PURPOSE: To relatively shorten the travel distance of an air blow-off nozzle having a blow-off port which is elongated in the longitudinally direction and which is positioned facing the upper surface of the vehicle, so as to shorten the time required for draining water from the upper surface of a vehicle by arranging the blow-off nozzle on a frame so as to be movable in a lateral direction orthogonal to the longitudinal direction of the vehicle.

CONSTITUTION: A water drain device is adapted to remove water drops, dust or the like sticking to the outer surface of a vehicle body during the final visual inspection after completion of the assembly of a vehicle body V. In this case, a bonnet blow-off nozzle 3 facing the bonnet VB of the vehicle V, a roof blow-off nozzle 3 facing the roof VR of the vehicle V and a trunk blow-off nozzle 4 facing the trunk VT of the vehicle V are arranged on a frame 1 striding the vehicle V so as to be movable in the widthwise direction orthogonal to the longitudinal direction of the vehicle V. Meanwhile, an upper surface blow-off nozzle 5 facing the upper surface of the vehicle body V and a pair of side surface blow-off nozzles 6 facing the side surfaces of the vehicle V are stationarily arranged.