[(6-Heptylsulfonyl)hexylthio]methyl-substituted poly(oxyethylene) bearing a very polar sulfone group in the middle of the alkyl side chain was successfully synthesized by the reaction of poly[oxy(chloromethyl)ethylene] and (6-heptylsulfonyl)hexyl thioacetate with sodium ethoxide in N,N-dimethylacetamide. The ordered phase of the polymer was studied using X-ray diffraction, differential scanning calorimetry, and IR spectroscopy. The polymer was found to be liquid crystalline, although not having any conventional mesogenic group. It was suggested that the highly polar sulfone group in the side chain induces the self-assembly of the liquid crystal-line phase.