To endow an actuator function on a tube fitting by fitting a shaft shaped moving body operated by a pressure fluid supplied to a tube into a hole for a pressure fluid passage penetrated into a main body of the tube fitting connected to a tube for supplying the pressure fluid, freely to reciprocate with a prescribed stroke.

A rod 8 as a shaft shaped moving body is fitted to a hole 3 for a pressure fluid passage penetrated into a main body 2 to be reciprocatable with a prescribed stroke. A cap 6 is screwed around a front end disposed on a side opposite to a rear end where a nut 4 of the main body 2 is screwed, a recessed groove 12 is disposed on a part faces to a front end surface of the main body 2 in the cap 6, a ring shaped collar 14 is interposed between the recessed groove 12 and the front end surface of the main body 2, an O-ring 13 adjacently arranged on the collar 14 and a hole 11 opened on the cap 6 are slidably penetrated by the rod 8, and the hole 3 for the pressure fluid passage penetrated in the main body 2 is set in an air-tightly condition. It is thus possible to form a structure in a compact size, and it is also possible to reduce the number of parts to reduce cost.