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.
