A vehicle injector mounting structure is provided to allow an injector to be mounted on any part of an intake manifold regardless of the type of a vehicle. An injector(10) is mounted on an intake manifold(2) through an adaptor(100) coupled to the injector. The intake manifold has a mounting hole(200), and the adaptor has one side with a stopper(122) protruded outwardly in such a manner that the stopper gets caught at the mounting hole of the intake manifold. The adaptor includes an insertion portion(120) having the stopper, and an extended portion(110) extended from the insertion portion. The insertion portion of the adaptor is equipped with an O-ring(130) and a guide ring(140) which are compressed between the intake manifold and the extended portion of the adaptor so as to maintain air-tightness and water-tightness between the adaptor and the mounting hole.
