Abstract: [Problem] To provide a trimethylenenorbornane production process capable of producing trimethylenenorbornane, which serves as a raw material of adamantane, with a high efficiency in a raffinate or a heavy raffinate heavy, through high efficiency production of dicyclopentadiene, which serves as a raw material of trimethylenenorbornane, without additionally using a dicyclopentadiene hydrogenation unit or a cyclopentadiene dimerization column.