This invention provides a method of manufacturing a curable petroleum resin and a curable petroleum resin obtained therefrom. The method includes (a) a process of thermally polymerizing a composition for polymerization which includes silanes and monomers, including cyclic olefins having at least one ethylenically unsaturated group selected from among C5 fractions, C9 fractions, and dicyclopentadiene of naphtha cracking, thereby enabling petroleum resins, which are thermoplastic resins, to be applied as reactive adhesives, and ultimately being capable of providing eco-friendly reactive adhesives.