A drift tube manufacturing method and a drift tube which can reduce cost while securing an adequate level of particle beam focusing performance. The method includes: a magnet housing stage of housing a predetermined number of permanent magnets in a housing, which has a through-hole at a center part and an annular magnet housing space on an outer circumferential side of the through-hole; a welding stage of setting a lid for covering the opening part on the opening part; and welding the lid and the housing by laser beam welding. At least a surface of the housing and a surface of the lid are formed of copper.