1. The polyester binder resin for coating is obtained by copolymerizing a dibasic acid component; a diol component containing 1-60 mol of isosorbide with respect to the total diol components; and 1-50 wt% of lactic acid or a compound derived therefrom with respect to the total resin polymerization reactants, and has the structure in which a dibasic moiety derived from the dibasic acid component, a diol moiety derived from the diol component, and a hydroxy monobasic acid moiety derived from said lactic acid or a compound derived therefrom are repeated.