To attach and detach an adsorbing vessel to and from an apparatus main body with a simple operation without necessitating a tool for the attachment and the detachment.

A plurality of guide grooves 27 are provided on the inner circumferential surface of an apparatus side coupling cylinder 26 provided in an apparatus main body 11, and engaging projecting parts 56 guided by the respective guide grooves 27 are provided on the outer circumferential surface of a vessel side coupling cylinder 43 of a drying agent cylinder 12a. Each guide groove 27 is composed of an axial directional guide groove 27a extending in the central axis line direction and a circumferential directional groove 27b extending from the lower end of the axial directional groove 27a in the circumferential direction. When both coupling cylinders 26 and 43 satisfy a prescribed rotation-position relationship, each engaging recessed part 56 is guided by the axial-direction guide groove 27a to bring both cylinders 26 and 43 in an inserted state to each other. In the inserted state, each recessed part 56 is guided by the circumferential directional guide groove 27b to relatively rotate the vessel side coupling cylinder 43 by 45° to the apparatus side coupling cylinder 26, and both cylinders are coupled so that the vessel side coupling cylinder 43 cannot be pulled out from the apparatus side coupling cylinder 26 in the rotation-position relationship.