To obtain an ethylene-based copolymer having excellent transparency, mechanical properties and viscoelasticity, to provide a method for producing the copolymer and to obtain a film, a sheet and a molding product having excellent transparency, mechanical properties and viscoelasticity.

This ethylene-based copolymer comprises ethylene and at least one kind of a monomer to be subjected to an addition polymerization, containing a vinyl compound (A) represented by a structural formula CH2=CH-R containing a saturated hydrocarbon group R in which the steric parameter Es of the substituent group R is ≥-2.77 and ≤-1.64 and the steric parameter B1 of the substituted group R is ≥1.53 and ≤2.90. The ethylene-based copolymer has ≤119°C melting point (Tm) and the melt index MI (g/10 minutes) of the ethylene-based copolymer to the mol content (m) (mol%) of the vinyl compound (A) satisfying the equation 0.01≤MI≤18+m1.4.