The present invention relates to a process for producing a packing material for use in liquid chromatography which comprises aqueous suspension polymerizing vinyl acetate, a (meth)acrylic acid ester or a glycidyl monovinyl ester or ether with a monomer mixture composed mainly of a cross-linking monomer in the presence of a diluent selected from among epichlorohydrin and glycidyl ethers and thereafter removing it from the resulting polymer particles by ring-opening the epoxy groups in said diluent. This process provides a packing material for use in liquid chromatography which is uniform and porous and moreover is excellent in mechanical strength.