PURPOSE: To improve the surface condition of the inner and outer surfaces which are after working and to increase the out-of-roundness of the inner surface by forming the large diameter part with bulging from the inner side by liquid pressure bulging work and by forming the small diameter part with pressing from the outer diameter side by reducing work.

CONSTITUTION: The straight pipe shaped pipe stock having the intermediate diameter of small diameter parts 2, 3 and large diameter part 4 is used and set into a die. High pressure water or oil is enclosed into the pipe stock by operating a booster 42 and the compression force beyond the yielding pint is applied in the axial direction on the pipe stock by operating cylinder mechanisms 34, 35. The formation of the semifinished product A having large diameter part is attain with high accuracy accordingly. Small diameter parts 2, 3 are formed by performing the reducing of extrusion, etc. on the both ends after obtaining the semifinished product A. Terminal fitting parts 6, 7 are formed by well-known upsetting and serration work, etc.