A sensor apparatus for a vehicle includes a protector, a holder, and a sensor. The protector is inserted into an insertion hole of a deck of the vehicle. The protector includes protector hooks formed thereon. The holder is inserted into the insertion hole and coupled to the protector so as to be constrained by the protector hooks. The holder includes holder hooks formed so as to be hooked to an inner surface of the deck. The sensor is coupled to the holder.