It is an object of the invention to provide a material for -insulating substrate, a printed board, a laminate, copper foil with resin, a copper-clad laminate, a polyimide film, a film for TAB and a prepreg, which are excellent in physical properties, dimensional stability, heat resistance, flame retardancy etc. and exhibit an excellent flame retardant effect particularly by a shape retention effect at the time of combustion The invention provides a material for insulating substrate, comprising 100 parts by weight of a thermoplastic resin or a mixture of a thermoplastic resin and a thermosetting resin and 0.1 to 100 parts by weight of a layered silicate.