A tubing including an overlap portion formed by the first and second circumferential end portions overlapping and joined with each other, and a fluid leakage preventing member for preventing pressurized fluid from leaking from the tubing upon the tubing being subjected to hydrostatic forming. An apparatus and method for hydrostatic forming of a tubing having an overlap portion. The apparatus includes a die and a nozzle having fluid leakage preventing means for preventing the pressurized fluid supplied into the tubing from leaking from a clearance between the first and second circumferential end portions of the overlap portion of the tubing at the longitudinal end portions of the tubing.