A polar monomer-olefin copolymer comprising a polar monomer unit in an amount of 50 to 75% by mol and an olefin unit in an amount of 25 to 50% by mol, and containing a chain structure consisting of two or more olefin units; a process for producing said copolymer comprising the step of radically copolymerizing 100 parts by mol of an olefin with 1 to 100 parts by mol of a polar monomer; and a process for producing said copolymer comprising the step of radically copolymerizing an olefin having a concentration in a polymerization reactor of 0.04 to 100 mol/liter with a polar monomer having a concentration therein of 0.01 to 25 mol/liter.