We conducted an extremely wide field survey of z ~ 6 Lyman break galaxies (LBGs) to precisely derive their bright end surface density overcoming the bias due to cosmic variance. We selected out LBG candidates in the Subaru/ XMM-Newton Deep Survey Field (SXDS) over the total of 1.0 deg2 sky area down to z'AB = 26.0 (≳ 3σ, 2"0 aperture) using i' - z' > 1.5 color cut. This sample alone is likely to be contaminated by M/L/T dwarfs, low-z elliptical galaxies, and z ~ 6 quasars. To eliminate these interlopers, we estimated their numbers using an exponential disk star count model, catalogs of old ellipticals in the SXDS and other field, and a z ~ 6 quasar luminosity function. The finally derived surface density of z ~ 6 LBGs was 165 mag-1 deg-2 down to z'AB = 26.0 and shows good agreement with previous results from the narrower field survey of HST GOODS.