To obtain an adhesive for mutually bonding a polyolefin material or bonding a polyolefin material to the other material.

This adhesive is obtained by mixing a main agent comprising a graft type polyester polyol obtained by subjecting a polyesterpolyol having hydroxyl group at ends to ester bonding to a polyfunctional carboxylic acid having ≥3 functional groups as a main agent with a curing agent consisting mainly of a polyisocyanate compound and used as an essential component. It is desirable that ≥70 mol% acid component of polyesterpolyol having hydroxyl group at ends is an aromatic polybasic acid and ≥50 mol% of its alcohol component is a ≥5C straight-chain alkyldiol.