Patent ID: 8366639

Claim:
A balloon for measuring a pressure related to an oral cavity, comprising: a pressure-receiving portion that is formed of an elastic material and that internally forms a closed space, the pressure-receiving portion being configured to be placed in the oral cavity; and a tubular portion that is formed integrally with the pressure-receiving portion, the balloon being configured to detect an air pressure in an interior of the pressure-receiving portion by communicating the interior of the pressure-receiving portion with a pressure detector through an opening end of the tubular portion, wherein the pressure-receiving portion and the tubular portion are formed of a thermoplastic elastomer, and a transverse cross-section of the pressure-receiving portion orthogonal to an axial direction of the tubular portion has a flat outer circumferential shape with an oblateness f=(A−B)/A, where A represents a length of a major axis of the outer circumferential shape and B represents a length of a minor axis thereof, being set to a range of 0.1≦f≦0.7 at a position at which the length A of the major axis is at a maximum.