An apparatus for evaluating a watertight state of a vehicle and a method for controlling the apparatus may include an automatic ejection device having a plurality of nozzles to automatically eject water to the glass on the inside of the vehicle, an additional ejection device configured to additionally eject water separately from the automatic ejection device, a plurality of cameras configured to photograph flows of the water when water is ejected by the automatic ejection device and the additional ejection device, so that evaluation of a watertight state between the vehicle body and the glass may be preliminarily verified by allowing the water to a lower end portion of the glass through the automatic ejection device and the additional ejection device, photographing the flows of the ejected water through the cameras, and detecting whether water is introduced into the internal of the vehicle.