To provide an instrument with which the oral cavity-pressure including the tongue pressure of a patient can be measured easily and a disposable probe used for the instrument.

The oral cavity-related pressure measuring instrument is constituted to use the probe containing a balloon 1 formed of an elastic or flexible material and a holder coupled with the balloon 1 and to detect the air pressure in the balloon 1 by means of a pressure detecting section 7 communicating with the inside of the balloon 1. The probe is connected to the detecting section 7 through a main body tube 6 which communicates the inside of the balloon 6 to the detecting section 7. The coupling between the probe and tube 6 is constituted in a freely attachable/detachable state.