To obtain a resin composition for attaining high flame retardance without using a halogen and a phosphorus compound, an insulating material and a multilayer wiring board.

This resin composition is a resin composition useful for a buildup material for a multilayer wiring board and comprises a resin and an inorganic compound having 300-800°C softening point. This insulating material is obtained by laminating the resin composition to a carrier film, etc. This multilayer wiring board is obtained by disposing the insulating material on one side or both the sides of an inner layer circuit board, heating and pressurizing.