To provide a work holding jig which is repeatedly used in a simple procedure when grinding an outer surface of a cylindrical work and capable of ensuring the grinding accuracy.

When grinding an outer surface of a cylindrical work, a work Wa is held by a pair of resin-made conical members 3 for a holding jig to hold the work at the center position in a case of the work Wa in which a cylindrical hole is a through hole, or an inner surface of a cylinder is held by expanding a resin-made expanding member 4 by a tapered member 5 in a case of a work Wb in which the cylinder hole is a bottomed one, or a male screw is screwed to a screw hole in a case of a work Wc in which the cylindrical hole is a screwed hole. In any case, fitting parts 2s, 5s and 10s to fit a rotary block and a center hole c are provided.