To provide alloy cast iron having high strength and heat resistance for producing a piston ring in particular of an internal combustion engine.

This alloy cast iron mainly has a pearlite type fundamental structure contg. spheroidal or vermicular precipitated graphite and has the following compsn. of by weight, 2.5 to 4.0% carbon, 1.5 to 4.0% silicon, 0.2 to 2.0% manganese, ≤0.35% phosphorus, ≤0.03% sulfur, ≤3.0% chromium, ≤1.5% vanadium, ≤2.5% molybdenum, ≤0.2% nickel, 1.0 to 3.5% copper, 0.02 to 2.5% aluminum, 0.02 to 2.5% magnesium, and the balance iron.