Abstract: In an oxygen concentrator, a housing has a through hole formed therein, and a handle portion provided adjacent to the through hole. The through hole is formed so as to extend toward an other side in an axial direction of the housing from a first opening, the first opening being defined at least by a back-side end of a top face portion, two extension portions, and an upper end of the handle portion, and has an interior space continuously extending between the first opening and a second opening defined at least by a lower end of the handle portion and an upper end of the back face main body portion and disposed on the other side in the axial direction with respect to the first opening.

Abstract: A nasal cannula in which a pair of nostril inserts (130) are provided on a base (120) provided at the distal end of a tube (110) such that the nostril inserts (130) communicate with the tube (100). The base (120) and the nostril inserts (130) are integrally formed so as to elastically deform to an appropriate extent. The nostril inserts (130) have an appropriate length. When the nostril inserts (130) are inserted into the right and left nostrils, respectively, of a patient, the nostril inserts (130) hold at least one of the columna nasi and the nasal septum from opposite sides with an appropriate elastic force, whereby the nostril inserts (130) are attached to the nostrils.