TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Monomer composition containing epichlorohydrin, and trialkylaluminum in which all the alkyl groups are linear alkyl groups is subjected to ring-opening polymerization in the presence of catalyst which comprises onium salt of compound comprising atom of group 15 or 16 to obtain polyether compound containing epichlorohydrin unit. The obtained compound is reacted with imidazole compound, to obtain imidazolium chloride structural-unit containing polyether compound. Anion exchange reaction of the obtained polyether compound is carried out using salt comprising anion and metal cation to obtain the polyether compound. Preferred Compound: The ratio of the repeating units (II) among the repeating units (I) is 2 mol% or more. Preferred Definitions:    X-=OH-, SCN-, BF4-, PF6-, ClO4-, (FSO2)2N-, (CF3SO2)2N-, (CF3CF2SO2)2N-, CH3SO3-, CF3SO3-, CF3COO- or PhCOO-;and    A=H or (halo)alkyl.    EXAMPLE - (In g) tetra-n-butylammonium bromide (3.22) and toluene (50 ml) were cooled to 0 degrees C and reacted with triethylaluminum (1.256) in n-hexane (10 ml) to obtain a catalyst composition. Epichlorohydrin (10.0) was added to the obtained catalyst composition, and polymerized to obtain oligomer having bromoethyl group as transparent oil-like substance (9.9) with number average molecular weight of 1050 and molecular weight distribution of 1.35. The obtained oligomer (5.0), acetonitrile (10.0) and 1-methylimidazole (12.1) were heated to 80 degrees C. Mixture of toluene/methanol/water was used to wash the reaction material and the organic phase was removed. The water phase was dried under reduced pressure at 50 degrees C to obtain 1-methyl-imidazolium-containing oligomer (9.4). The obtained oligomer (2.5), potassium hydroxide (2.0) and ion-exchange water (20 mL) were reacted at room temperature for 30 minutes, and dried under reduced pressure at 50 degrees C for 1 hour to obtain imidazolium structure containing polyether compound having high ionic conductivity.