We demonstrate the luminosity dependence of the covering factor (CF) of active galactic nuclei (AGNs), based on AKARI mid-infrared all-sky survey catalog. Combining the AKARI with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 243 galaxies at 9 m and 255 galaxies at 18 m. We then identied 64 AGNs at 9 μm and 105 AGNs at 18 μm by their optical emission lines. Following that, we estimated the CF as the fraction of type 2 AGN in all AGNs. We found that the CF decreased with increasing 18 μm luminosity, regardless of the choice of type 2 AGN classification criteria.