PURPOSE: To obtain the subject composition composed of a polyester resin, a specific epoxy resin, etc., a polyisocyanate, a polyamine and a flame-retarding assistant at specific ratios, containing a prescribed amount of halogen, having excellent chemical resistance and suitable for flame-retardant flexible printed circuit board, etc.

CONSTITUTION: This adhesive composition is composed of (a) a polyester resin, (b) an epoxy resin containing ≥2 epoxy groups in one molecule (e.g. bisphenol A epoxy resin), (c) an epoxy resin containing ≥3 epoxy groups in one molecule (the sum of the components (a) to (c) is 100 pts.wt., and the amounts of (a) to (c) satisfy the formulas I and II), (d) 5-50 pts.wt. of a polyisocyanate such as tolylene diisocyanate, (e) 1-20 pts.wt. of a polyamine and (f) 3-30 pts.wt. of a flame-retarding assistant (e.g. Sb2O3). The halogen content in the resin component consisting of the components (a) to (e) is ≥18wt.%. This flame- retardant flexible printed circuit board can be produced by subjecting a polyester film to a low-temperature plasma treatment and laminating and integrating a metal foil to the polyester film using the composition as an adhesive.