An object of the present disclosure is to provide a copolymer excellent in fracture resistance, ozone resistance and wear resistance. In order to achieve the object, the present disclosure provides a copolymer containing at least an ethylene unit, a C4-10 non-conjugated olefin unit and a conjugated diene unit, wherein a content of 3,4 or 1,2-vinyl bond in the conjugated diene unit is equal to or larger than 30 mol %.