A tube fitting for attaching and detaching a tube. The tube fitting includes a tubular main body, a sleeve being tubular-shaped and being fixed in the main body with axial lines of the main body and the sleeve coincided with each other. A locking member includes a ring part and a plurality of extended parts extending from the ring part toward an axial direction and being mounted in the sleeve in a state where axial lines of the ring part and the sleeve are coincided with each other and being movable in the sleeve in an axial direction and in a circumferential direction.