PROBLEM TO BE SOLVED: To improve maintainability by making attachment/detachment of components, for example, a sieve bed and a manifold, easy and reduce the size of an installed device itself.SOLUTION: In an oxygen concentrator 10, when a projecting connection pipe 42a of a sieve bed 421 is inserted into an opening part 71 in a joint part 70, the projecting connection pipe 42a is attachably/detachably fixed to lock claws 713. A joint support part 132 supports the joint part 70 to be freely moved toward a pulling direction of the projecting connection pipe 42a. A side wall 11a is disposed so as to face a push ring 711 which forms an opening edge of the opening part 71. When the projecting connection pipe 42a is pulled toward the pulling direction, the push ring 711 touches the side wall 11a following the pulling of the projecting connection pipe. Then the push ring 711 is moved toward an insertion direction of the projecting connection pipe, and the fixed state of the projecting connection pipe 42a to the lock claws 713 is released. This allows the projecting connection pipe 42a to be pulled out of the joint part 70.
