To provide a polyether ester block copolymer which has surface hardness suitable to be applied to a structural member and excellent in sound deadening quality and tribological property, a polyether ester block copolymer of the present invention comprises (a) aromatic dicarboxylic acid unit, (b) 1,3-propanediol and/or 1,4-butanediol unit and (c) long chain diol unit mainly including polyoxytrimethylene glycol, wherein the durometer hardness (type D), measured according to the principle of the method described in JIS K6253, is 40 or larger and 78 or smaller.