To obtain the subject copolymer capable of giving films with excellent heat sealability, slipperiness and anti-blocking tendency and enabling high-speed film formation process.

This copolymer is an ethylene-propylene random copolymer satisfying the requirements described below: (1) ethylene unit content (α) determined by 13C-NMR is 0.2-10 wt.%, (2) the elution amount (Wp) between (Tp-5)°C and (Tp+5)°C is ≥20 wt.% (Tp(°C) is the principal elution peak temperature in the ascending temperature partition chromatograph), and (3) the elution amount at ≤0°C (W0, wt.%) in the ascending temperature chromatograph and α satisfy the relationship: W0≤[(3+2α)/4].