A nozzle 33 is formed on a distal end side of a cylinder 3. The nozzle 33 has an intermediate portion 3b formed such that a tip 7 is freely attachable thereto and detachable therefrom. The intermediate portion 3b of the nozzle 33 is formed with an annular projection 3e for retaining the tip 7. The tip 7 has a thick portion 7a provided in a root portion thereof and formed larger in diameter than a root portion 3a of the nozzle 33 to be abuttable against a tip releasing member 11. Along an inner periphery of the root portion of the tip 7, an annular projection 7b is formed to contact with the annular projection 3e of the nozzle 33 thereby providing a seal with the nozzle 33. Both the annular projections 3e and 7b of the nozzle 33 and the tip 7 are arranged to reach a position where a sound of abutment is produced between the root end surface of the tip 7 and the shoulder of the nozzle 33 at the completion of fitting of the tip 7 onto the nozzle 33.