Fine tubular fibers composed of C60 and C70 fullerene molecules were successfully fabricated by the liquid–liquid interfacial precipitation method. The walls of the tubular fibers were crystalline, and the fullerene molecules were densely packed along the growth axis of tube wall. The tubular structures are called “fullerene nanotubes.” The inner diameter and the outer diameter of C70 tubes showed a linear relationship, suggesting a constant wall thickness of the tubes. The tubular structures composed of C70 molecules could be formed when their diameter was larger than about 240 nm. The fullerene tubes were successfully fabricated by using a C60-C70 soot as well. The formation of fullerene nanotubes can be understood by assuming a mechanism of core dissolution of the solvated fullerene nanowhiskers.