The present invention relates to an interlayer insulating composition for a multilayer printed wiring board including: an epoxy resin including a naphthalene-modified epoxy resin, a cresol novolac epoxy resin, and a rubber-modified epoxy resin; a thermoplastic resin; a curing agent; and an inorganic filler and a multilayer printed wiring board including the same as an insulating layer. The present invention can provide an insulating composition excellent in adhesion between an insulating layer and a Cu layer to secure normal operation and reliability of a final substrate. Further, since the present invention properly includes an epoxy resin and a thermoplastic resin regardless of an increase in the content of an inorganic filler, it is possible to secure the reliability of the substrate by preventing an insulating film from being brittle and improving toughness of the insulating film while maintaining a low thermal expansion rate.