This positioning system positions an affected area of a patient with respect to radiation from an irradiation nozzle (12). A hole is dug in the floor surface (15) of a treatment room. The hole is covered with a movable floor surface (16). An arm part (17) of the positioning system supports a tabletop (11). When the patient is to be laid on the tabletop (11), first the movable floor surface (16) is lowered into the hole by a floor lifting mechanism (6). A therapy table lifting mechanism (14) then lowers the arm part (17) and tabletop (11). In doing so, the lower side of the arm part (17) goes into the hole so that the arm part (17) does not interfere with the floor surfaces (15, 16). Consequently, the tabletop (11) can be lowered to a position which is easy for the patient to lie down on. After the patient lies down on the tabletop (11), the tabletop (11) is raised by therapy table lifting mechanism (14). The movable floor surface (16) is returned to the same height as that of the floor surface (15) of the therapy room.
