An overheating detection unit is attached between an oxygen concentrator and a cannula, making it possible to reliably detect a high-temperature environment to cut the supply of oxygen when a user inhales oxygen using the cannula and is exposed to a fire or an abnormal high-temperature environment. An overheating detection unit includes a main body including a connecting member connected to an oxygen outlet and an oxygen outlet portion connected to a tube and also includes a housing covering the main body. The main body includes a temperature sensor in the oxygen outlet portion to detect the temperature of the oxygen outlet portion and a blocking structure portion that blocks a passage between the connecting member and the oxygen outlet portion to cut the supply of oxygen when the temperature sensor detects a temperature equal to or higher than a predetermined temperature.
