An oral cavity insertion instrument which is to be attached to a monitor device having a long scope portion is provided. The oral cavity insertion instrument is adapted to be used by being inserted into an oral cavity and has a long cover member having a bore which extends in a longitudinal direction thereof, wherein the scope portion of the monitor is adapted to be inserted into the bore. The oral cavity insertion instrument also has a long tongue depressor in the form of a plate. The tongue depressor is provided adjacent to and in contact with the cover member along the longitudinal direction thereof. The oral cavity insertion instrument includes an attachment unit used to attach the cover member to the monitor device. The tongue depressor includes a tip end having a width greater than that of the cover member. A pharyngoscope apparatus provided with the oral cavity insertion instrument is also provided.
