We studied the energy spectrum and the large-scale fluctuation of the X-ray background with the ASCA GIS instrument based on the ASCA Medium Sensitivity Survey and the Large Sky Survey observations. A total of 91 fields with Galactic latitude |b| > 10 ° were selected with a sky coverage of 50 deg2 and 4.2 Ms of exposure. For each field, non X-ray events were carefully subtracted and sources brighter than ~ 2 × 10-13 erg cm-2 s-1 (2 - 10 keV) were eliminated. Spectral fits with a single power-law model for the individual 0.7-10 keV spectra showed a significant excess below ~ 2 keV, which could be expressed by an additional thermal model with kT ≅ 0.4 keV or a steep power-law model with a photon index of Γsoft ≅ 6. The 0.5 - 2 keV intensities of the soft thermal component varied significantly from field to field by 1 σ = 52.1+4.2-4.6 %, and showed a maximum toward the Galactic center. As for the hard power-law component, an average photon index of 91 fields was obtained to be Γ hard = 1.412 ± 0.007 ± 0.025 and the average 2-10 keV intensity was calculated as FhardX = (6.38 ± 0.04 ± 0.64) × 10-8 egr cm-2 s-1 sr-1 (1σ statistical and systematic errors). The 2-10 keV intensities show a 1 σ deviation of 6.49+0.56+0.61 %, while deviation due to the reproducibility of the particle background is 3.2%. The observed deviation can be explained by the Poisson noise of the source count in the f.o.v. (~0.5 deg2), even assuming a single log N-log S relation on the whole sky. Based on the observed fluctuation and the absolute intensity, an acceptable region of the log N - log S relation was derived, showing a consistent feature with the recent Chandra and XMM-Newton results. Fluctuation of the spectral index, on the other hand, implied a large amount of hard sources and a large variation in the intrinsic source spectra (ΓS ≅ 1.1 ± 1.0). According to the recent Chandra results reported by Rosati et al. (2002), the X-ray background in 2-10 keV has been resolved into discrete sources by 73-96% at a flux limit of S >~ 4.5 × 10-16 egr cm-2 s-1.