An adapter structure for mounting a boost pressure sensor according to the present invention, includes: an intake manifold mounting unit which is provided at an intake manifold and is formed with a penetrating hole at one side portion thereof to communicate with an inside of the intake manifold; a pressure sensor adapter which has a lower portion separably coupled to the intake manifold mounting unit, is made of a heat resistant or heat isolating material, and has a channel which is formed at one side portion thereof, transmits intake air pressure from the penetrating hole of the intake manifold mounting unit to the outside, and has an inner space of which a portion far from the penetrating hole of the intake manifold mounting unit is greater than a portion close to the penetrating hole of the intake manifold mounting unit; a boost pressure sensor which is mounted at an upper portion of the pressure sensor adapter so that a pressure detection portion is tightly coupled to an upper end portion of the channel of the pressure sensor adapter, detects the intake air pressure through the channel of the pressure sensor adapter, and sends a generated intake air pressure signal to an electronic control unit of an engine; and a fixing unit which separably fixes the boost pressure sensor to the intake manifold mounting unit by the media of the pressure sensor adapter.