A polyether-polyol compound represented by the compositional formula C3nH6n+2O2n+1, wherein n is an integer of 4 or more, wherein the polyether-polyol compound has a total number of 1,2-diol unit and 1,3-diol unit of [(n/2)+1] in a case where n is an even number of 4 or more, or a total number of 1,2-diol unit and 1,3-diol unit of [((n−1)/2)+1] and one hydroxyl group which is not involved in the units in a case where n is an odd number of 5 or more; a polyglycerol alkyl ether, a part of hydroxyl groups in a polyglycerol being substituted by an alkyl group, wherein the polyglycerol is the polyether polyol compound mentioned above; and an ester prepared by the process comprising reacting the polyether-polyol compound mentioned above or the polyglycerol alkyl ether mentioned above with a fatty acid.