To provide a halogen free adhesive composition having excellent flame-retardancy and high electric insulation reliability without containing a halogen compound and excellent in a characteristic required for the flexible print wiring board, and to provide a flexible copper-clad laminated plate using it, a cover-lay and an adhesive sheet.

The flame-retardant adhesive composition contains (A) a non-halogen based epoxy resin, (B) a polyurethane resin, (C) a curing agent, (D) a curing accelerator, (E) a phosphorous flame retardant, and (F) an inorganic filler. The resin having a hydroxyl value of 5.0-15.0 KOHmg/g is used as (B) polyurethane resin, and a ratio of phosphorous element relative to the all organic resin component is made to 0.5-4.0 wt.%.