A structure includes a main tube 2 that contains a needlelike tubular body lumen 10 through which a needlelike tubular body 3 is inserted, with a distal section 4 of the main tube 2 having a first guide wire insertion section 33 and second guide wire insertion section 35, respectively containing a first guide wire lumen 38 and second guide wire lumen 52 through which a first guide wire 32 and second guide wire 34 are inserted. This structure further has a support tube 62 whose tip remains a free end, wherein this support tube 62 accepts a part of the second guide wire 34 extending out of the second guide wire lumen 52 and thereby supports the second guide wire insertion section 35.