Disclosed is a biaxially oriented, laminated polyester film having a lamination structure with at least two layers. At least one of the outermost layers of the film is a thin laminated layer A having a thickness of not more than 3 .mu.m. In the layer A, internally formed particles and specified agglomerated particles or mono-dispersed particles are present, or the mono-dispersed particles are present at a very small content. When the polyester film is used as a base film for magnetic recording media, the abrasion resistance of the film surface at a high speed can be greatly increased.