To provide a reactive polyolefin adhesive resin having excellent adhesion effect.

This reactive polyolefin adhesive resin comprises 10-80 wt.% reactive polyolefin of a siloxane group-grafted amorphous polyolefin, 10-70 wt.% viscosity increasing agent of a petroleum resin, a terpene resin or a rosin resin, and 0.1-3 wt.% catalyst of an organic tin-based catalyst, a phosphate-based catalyst or a metal complex catalyst.