COPOLYMER RUBBER, RUBBER COMPOSITIONS AND RUBBER MOLDINGS

To provide a copolymer rubber excellent in kneading processability and extrusion processability and a rubber composition containing it and provides a crosslinked rubber-molded product excellent in sealability and shape retention obtained from the composition. A random copolymer rubber of ethylene (A), an ±-olefin (B) having 3 to 20 carbon atoms and a non-conjugated polyene (C) that satisfies the following (1) to (5): (1) the said random copolymer rubber contains structural units of (A) and structural units of (B) in a molar ratio of 40/60 to 95/5 in terms of (A)/(B), (2) the content of structural units of (C) is 0.01 to 5 mol%, (3) the intrinsic viscosity [·] measured in decalin at 135°C is from 1.0 to 5.0 dl/g, (4) the Mw/Mn is 1 to 8, and (5) the value of P represented by the following formula is from 0.46 to 1.00. P = Ln ( intrinsic viscosity · ) - 5.0 × 10 - 5 × · * 10 wherein Ln is a natural logarithm and ·*(10) is viscosity (Pa.sec) measured at 10 rad/sec and at 190°C.