To provide an adhesive composition free of both halogen and phosphorus, expressing high flame retardancy, adhesivity and flexibility, and excellent in high-temperature bendability with high heat resistance without impairing its electrical properties, and to provide a flexible printed wiring board material using such an adhesive composition.

The adhesive composition as a halogen-free and phosphorus-free flame retardant resin composition essentially comprises an acrylonitrile-butadiene-modified epoxy resin, a curing agent, an elastomer and an inorganic filler. This composition is to be used as an adhesive for the flexible printed wiring board material.