Provided are a modified hydrocarbon resin that can provide a hot-melt adhesive composition with low odor, low Gardner color and high peel adhesion, a method for producing the resin, and the hot-melt adhesive composition. A modified hydrocarbon resin comprising a 1,3-pentadiene monomer unit, a C4-C6 alicyclic monoolefin monomer unit, a C4-C8 acyclic monoolefin monomer unit, an alicyclic diolefin monomer unit, and an aromatic monoolefin monomer unit, and containing a carboxyl group or acid anhydride group, wherein a weight average molecular weight (Mw), a Z average molecular weight (Mz), a ratio (Mz/Mw), a Gardner color scale of a 50 mass % toluene solution, a softening point, and an acid value are in specific ranges.