To provide a polyester resin having high adhesiveness to aluminum and polyester films or sheets and suitable for preparing coating, ink or adhesives, and to provide a polyurethane or polyurethane-urea resin obtained by using the polyester resin.

The polyester resin comprises an acid component and an alcohol component, the acid component containing 80 mol% or more of a benzene-o-dicarboxylic acid residue and/or a benzene-m-dicarboxylic acid residue and the alcohol component containing 50 mol% or more of a diol residue to which two or three alkylene groups having 8 or less carbon atoms are bonded through an ether bond, wherein the polyester resin has 0.4-4 mol/kg of hydroxy group on average at a molecular terminal and has melt viscosity at 100°C of 10 Pa s or less.