Provided are a carbon ion generating device and a tumor treatment apparatus using the same. The carbon ion generating device includes a carbon nanostructure, a carbon emitting structure, an ionizing structure, and an accelerator. The carbon emitting structure is configured to induce an emission of carbon atoms from one end of the carbon nanostructure. The ionizing structure is configured to ionize the emitted carbon atoms. The accelerator is configured to accelerate the ionized carbon atoms.