A one-pack type thermosetting composition comprising (A) at least one polyisocyanate compound having dispersed therein (B) at least one compound selected from the group consisting of (1) a solid polyfunctional compound having at least one functional group selected from the group consisting of hydrazino, primary amido and sulfamoyl groups, (2) a solid compound having at least one amidino group and (3) a solid compound having a heterocyclic ring and a plurality of active hydrogen atoms, or a one-pack type thermosetting composition comprising (A') a mixture consisting of (a) at least one polyisocyanate compound and (b) at least one high boiling polar compound, having dispersed therein (B') a solid polyfunctional compound having at least one active hydrogen atom. Said one-pack type thermosetting composition is storable and suitable for use in adhesives, sealing materials, coatings and shaped articles of resin.