There are provided an acrylic copolymer elastomer containing an acrylic acid polyalkylene glycol ester as a constituent, and a vulcanizable composition comprising said elastomer and a vulcanizing agent, which composition gives a vulcanizate excellent in cold resistance, heat resistance and oil resistance. The acrylic copolymer elastomer is obtained by copolymerizing(a) 45 to 89.9% by weight of a monomer represented by the formula ##STR1## wherein R.sup.1 denotes an alkyl group having 1 to 8 carbon atoms, and/or a monomer represented by the formula ##STR2## wherein R.sup.2 denotes an alkylene group having 1 to 8 carbon atoms, and R.sup.3 denotes an alkyl group having 1 to 8 carbon atoms,(b) 10 to 45% by weight of a monomer represented by the formula ##STR3## wherein R.sup.4 denotes a hydrogen atom or a methyl group, R.sup.5 denotes a hydrocarbon group having 1 to 8 carbon atoms, m is an integer of 2 to 10, and n is an integer of 2 to 3,(c) 0.1 to 10% by weight of a crosslinkable monomer, and(d) 0 to 30% by weight of a monoethylenically unsaturated monomer copolymerizable with components (a), (b) and (c).