To obtain the subject adhesive excellent in storage stability, long in pot life. excellent in curability and adhesiveness, useful for bonding a material such as wood to be bonded, having air permeability and water, comprising a specific isocyanate compound, a blowing agent and a filler in a specific ratio.

This adhesive for an air permeable material to be bonded comprises (A) 100 pts.wt. of a compound containing two or more isocyanate groups in the molecule and liquid at a room temperature, such as diphenylmethane diisocyanate, (B) 1-15 pts.wt. of a blowing agent to generate a gas when heated to 90-200°C, such as sodium bicarbonate, (C) 30-200 pts.wt. of a filler such as clay or calcium silicate and, optionally (D) 0.5-50 pts.wt. of a compound having reaction activity with an isocyanate group, such as ethylene glycol.