Abstract: An oxirane compound of following Formula (1), such as glycidol, is reacted in the presence of a powdered activated carbon, where necessary, with an initiator such as a polyhydric alcohol, an aliphatic alcohol, or an aliphatic carboxylic acid, to yield, for example, a polyglycidol, a polyglycidol alkyl ether, or a polyglycidol alkyl ester. wherein R1 and R2 may be the same as or different from each other and each represent one selected from hydrogen (H); a branched- or straight-chain alkyl group having one to thirty carbon atoms or an aryl group; and a functional group represented by —CH2-M, wherein M represents OH, F, Cl, Br, or —OR3, wherein R3 represents an alkyl group having one to twenty carbon atoms, allyl group, or an aryl group. A target compound can be obtained in a high yield with high quality according to this invention, from which the catalyst can be easily separated.