Abstract: An oxygen supply device includes: an oxygen tank (10); a pipe (20) which is connected to the oxygen tank; an oxygen mask (30); and a joint (40) which detachably connects the oxygen mask to the pipe, wherein the joint includes a socket (41) provided for the pipe and a plug (42) provided for the oxygen mask, wherein the oxygen mask includes a head attachment portion (31) attached to a head of the user, a pipe body (32) supported by the head attachment portion and having a front end portion extending toward the front side of the head of the user, and a tube (33) connecting a base end portion of the pipe body to the plug (42), and wherein the socket is provided for each component of the pipe, and the plug is connectable to each socket.