The photoinduced electrical transport properties of C59N@SWNTs are investigated by assembling them into FET devices. Our findings demonstrate that azafullerene molecules inside SWNTs make nanotube FET devices very sensitive to UV tight exposure by the decrease of source-drain current upon tight exposure. The photoswitching effect is found to be dependent on wavelengths of light and becomes negligible when the wavelength is increased to 480 nm. The photoinduced electron transfer is proposed to take place inside C59N@SWNTs due to the specific electronic structure of C59N, the heteromolecule bonding of which is sensitive to light.