To provide a polyester film easily torn and excellent in practicability.

This polyester film is a film comprising a specific ratio of a polyester (1) which mainly comprises a butylene terephthalate repeating unit and an acrylonitrile/styrene (AS copolymer) (2), and the AS copolymer (2) is dispersed in the polyester (1) as a specific particle. In this film, tear strength in the direction orthogonal to the long axis of the dispersed particle (T()), and tear strength in the direction of the long axis (T(s)) are in a relation of T()/ T(s)>1.0, and the film is easily torn in the direction orthogonal to the long axis of the dispersed particle. A multilayered film is prepared from this polyester film, and an easily openable packaging is structured with this multilayered film, and an easily openable lid material uses this multilayered film.