To provide a solventless two-component adhesive composition having desired low viscosity and desirably quickly exhibiting bond strength when firstly mixing together.

There is provided an adhesive composition, comprising: (a) a polyisocyanate component comprising (i) monomeric 4,4' methylene diphenyl diisocyanate and (ii) an isocyanate functional prepolymer that is the reaction product of a prepolymer reactant mixture comprising (A) monomeric 4,4' methylene diphenyl diisocyanate, and (B) one or more diol having OH equivalent weight of 225 or less, and (C) one or more triol having OH equivalent weight of 1,400 or more; and (b) a polyol component comprising one or more polyol.