A nitrile copolymer rubber composition including a nitrile copolymer rubber (A) containing 35 to 80 wt % of α,β-ethylenically unsaturated nitrile monomer units (a1), 19.5 to 64.5 wt % of conjugated diene monomer units (a2), and 0.5 to 20 wt % of α,β-ethylenically unsaturated carboxylic acid monomer units (a3) and an inorganic filler (B) with an aspect ratio of 30 to 2,000, wherein a content of the inorganic filler (B) with respect to 100 parts by weight of the nitrile copolymer rubber (A) is 1 to 200 parts by weight is provided.