A graphene optical device according to an embodiment of the present disclosure includes: an upper semiconductor layer; a lower semiconductor layer; and a graphene capacitor disposed between the upper semiconductor layer and the lower semiconductor layer, wherein the graphene capacitor includes a first graphene, a second graphene, and a first insulation layer disposed between the first graphene and the second graphene, wherein the first graphene and the second graphene partially overlap each other when viewed from the upper semiconductor layer toward the lower semiconductor layer.