According to the invention, a metal sheet laminated with a polyester resin film is prepared for a can material which can be sterilised by retort treatment and is distinguished by high resistance to milky changes during retort treatment after packing foods and drinks (beverages). According to the invention, before the retort treatment and after the lamination onto one or both sides of a metal sheet which is coated with a single layer of hydrated chromium oxide or a double layer comprising an upper layer of hydrated chromium oxide and a lower layer of metallic chromium, an optimum range of the relative densities and of the remaining proportion of biaxial orientation is adjusted in the laminated, biaxially oriented polyester resin film. About 10 to about 60% by weight of the film consists of polybutylene terephthalate and about 40 to about 90% by weight of the film consists of polyethylene terephthalate. The said film has a glass transition temperature of about 40 to about 70 DEG C.
