AN INDWELLING NEEDLE AND A METHOD OF MANUFACTURING THE INDWELLING NEEDLE. AN INDWELLING NEEDLE (10) IS PROVIDED WITH A PUNCTURE NEEDLE (18) CONSTRUCTED FROM A HOLLOW TUBULAR BODY (44), A CATHETER (20) MOUNTED TO THE OUTER PERIPHERAL SIDE OF THE PUNCTURE NEEDLE (18) AND CONSISTING OF A RESIN MATERIAL, AND AN INNER TUBE (22) MOUNTED BETWEEN THE PUNCTURE NEEDLE (18) AND THE CATHETER (20). A HELICAL GROOVE (30) EXTENDING ALONG THE AXIS OF THE CATHETER (20) IS FORMED IN THE INNER PERIPHERAL SURFACE OF THE CATHETER (20). A GAP (32) HAVING A PREDETERMINED WIDTH IS PROVIDED BETWEEN THE INNER PERIPHERAL SURFACE OF THE CATHETER (20) AND THE OUTER PERIPHERAL SURFACE OF THE INNER TUBE (22). THE GROOVE (30) HAS A CROSS-SECTION OF A SEMICIRCULAR SHAPE RECESSED TOWARD THE OUTER PERIPHERY OF THE CATHETER (20) AND IS HELD AIR-TIGHT AGAINST THE INNER TUBE (22).
