A polymer-extruded article produced by extrusion and vulcanization of a polymeric composition includes ethylene-.alpha.-olefin-nonconjugated polyene copolymer in an amount of 100 phr; carbon black in an amount ranging from more than 50 to 120 phr, the carbon black having an arithmetic average particle diameter of not smaller than 60 nm; a softener in an amount of not more than 100 phr; and thermo-expansive capsules in an amount ranging from 1 to 10 phr. The polymer-extruded article includes a surface section having an uneven surface derived from thermal expansion of the thermo-expansive capsules, and a rough surface derived from carbon particle of the carbon black and formed at the uneven surface derived form the thermal expansion of the thermo-expansive capsules.