PURPOSE: To provide a work holding jig for processing thin articles such as a pipe material in its shape of cantilever holding in the machine tool like a lathe, etc., and concentrically processing an unsymmetrical irregular-shaped articles a accurately and efficiently.

CONSTITUTION: In a work holding jig, a disc shape plate 3 is divided into three parts by arranging slits 4 with each proper width toward the periphery from the central part of a disc shape plate 2 formed by providing plural concentric circular shape grooves 3 on its one end surface and also this jig is composed of a disc shape plate 2 by which a surface opposite to the surface on which plural grooves 3 are formed can be installed on the chuck part 5 of a machine tool and a fan shape claw body 8 having projections 8A to be filted in the grooves 3 on the disc shape plate 2, and having its inner surface polished to an arbitrary size.