The invention provides compositions of chloroprene rubbers having improved vibration-damping properties under low temperature conditions without deterioration of mechanical properties, permanent compression set and tension fatigue in the final product. The chloroprene rubbers of the invention contain a xanthogen-modified chloroprene rubber and/or a mercaptan-modified chloroprene rubber in an amount of 100 parts by mass, a carbon black having an average particle diameter of 70 mn to 600 mn and a DBP oil absorption (as determined by Absorption A method of JIS-K6221) of 15 ml/100 g in an amount of 15 to 150 parts by mass, and a plasticizer represented by the chemical formula R1COO—(CH2)8—COOR2 wherein R1 and R2 each represent an alkyl group having 1 to 7 carbons.