To provide a measuring apparatus capable of grasping easily an air pressure state in a thoracic cavity without depending on skill or experience of a doctor, by measuring simply air pressure in the thoracic cavity.SOLUTION: There is provided a measuring apparatus 1 for air pressure in a thoracic cavity, which is a measuring apparatus emitting at least either of a first signal and a second signal described as follows: (1) the first signal: a signal emitted when the air pressure in the thoracic cavity to the atmospheric-pressure is higher than a first prescribed negative pressure value which is a negative value, (2) the second signal: a signal emitted when the air pressure in the thoracic cavity to the atmospheric-pressure is lower than a second prescribed negative pressure value which is a negative value.SELECTED DRAWING: Figure 2【課題】簡便に胸腔内の気圧を測定し、医師の技量や経験に依らず胸腔内の気圧状態を容易に把握し得る測定装置を提供する。【解決手段】胸腔内気圧の測定装置１であって、次に記載する第１信号および第２信号の少なくとも一方を発することを特徴とする測定装置。（１）第１信号：大気圧に対する胸腔内気圧が、負の値である第１所定陰圧値よりも高いときに発せられる信号（２）第２信号：大気圧に対する胸腔内気圧が、負の値である第２所定陰圧値よりも低いときに発せられる信号【選択図】図２
