To obtain a solid rubber vulcanizate having excellent properties such as permanent compression set for many hours, sealing performance, low- temperature properties, processability, appearance, or the like.

An oil extended copolymer (III) for the solid rubber vulcanizate comprises 100 pts.wt. of an ethylene-α-olefin-nonconjugated diene copolymer (I) satisfying the following conditions of (a) the weight ratio of ethylene/α-olefin is 73/27-40/60, (b) the content of the nonconjugated diene is 20-36 by an iodine value, (c) the measured Mooney viscosity (ML1+4 (121°C) in JIS K-6300 Mooney viscosity test) of a mixture obtained by mixing 100 pts.wt. of the copolymer (I) with 20 pts.wt. of an extender oil (II) is 100-180 and (d) the Q value (weight- average molecular chain length/number-average molecular chain length) in gel permeation chromatography(GPC) measurement is 3-5 and 10-90 pts.wt. of the extender oil (II).