Semiconductor carbon nanotube was grown on oxided silicon wafer with atmosphere pressure chemical vapor deposition (APCVD) method and investigated the electrical property after thermal oxidation at $300^{circ}C$ in air. The electrical property was measured at room temperature in air after thermal oxidation at $300^{circ}C$ for various times in air. Semiconductor carbon nanotube was steadily changed to metallic carbon nanotube as increasing of thermal oxidation times at $300^{circ}C$ in air. Some removed area of carbon nanotube surface was shown with transmission electron microscopy (TEM) after thermal oxidation for 6 hours at $300^{circ}C$ in air.