To make it possible for a patient of home oxygen therapy to continue receiving treatment safely and comfortably by eliminating inconvenience in handling of an oxygen supply tube in the patient's residence.

Oxygen piping lines 3, 3, ..., are preliminarily installed between an oxygen source 2 in the patient's residence and all the possible rooms or seats in the residence where the patient may go (referred to as destinations hereafter), and at a terminal connection part of a nasal cavity tube or an oxygen mask 1 and a terminal of the oxygen piping line, connectors a, b, ..., j with a self-closing valves which are instantaneously connectable with each other are respectively provided. When the patient moves to a desired destination, the nasal cavity tube or the like 1 is connected to the oxygen piping line 3 at the destination, so that supply of oxygen is receivable. The connector a is a female connector, while the connectors b, c, ..., j, are each a male connector with the self-closing valve. The connectors 1 and the connectors b, c, ..., j are instantaneously connectable with each other respectively.