A copolymer (A) of ethylene and an α-olefin having 6 to 8 carbon atoms, the copolymer having: (A-i) a melt tension (MT) at 190°C and a melt flow rate (MFR) which satisfy the relationship9.0×MFR-0.65 > MT > 2.2×MFR-0.84; (A-ii) a flow activation energy ((Ea)×10-4 J/molK) determined from a shift factor of time-temperature superposition of the flow curve, a carbon atom number (C) of the α-olefin in the copolymer and a α-olefin content (x mol%) in the copolymer which satisfy the following relationship(0.039Ln(C-2)+0.0096)×x+2.87 (A-iii) a haze value when formed into a film having a thickness of 30 µm by inflation molding, a density (d) in g/cm3 and a melt tension (MT) which satisfy the following relationships: when the flow index (FI) defined as a shear rate when the shear stress reaches 2.4×106 dyne/cm2 at 190°C and the melt flow rate (MFR) satisfy the relationshipFI ≥ 100×MFR,Haze