Secondary ion mass spectrometry (SIMS) is used to detect local distributions of hydrogen in various materials. However, it has been well-known that it is extremely difficult to analyze net hydrogen (I-IN) in metals with SIMS. This was because hydrogen, which is originated from moisture (H2O), hydrocarbon (CxHy) or other organic materials (CxHyOz) existing on a sample surface or in the SIMS chamber, is simultaneously detected in the SIMS measurement of the H-N, and the H-N and the background-originated hydrogen (H-BG) cannot be distinguished in a SIMS profile. The effective method for reductions and determinations of the H-BG in hydrogen measurements of metallic materials with the SIMS method has not been established. The present paper shows an effective method for reduction and estimation of H-BG in SIMS analyses of hydrogen charged into type 316 L austenitic stainless steel, and an accurate estimation method of the net charged hydrogen. In this research, a silicon wafer is sputtered by a primary ion beam of a SIMS near an analyzed area (silicon sputtering method) to reduce HOG. An uncharged type 316 L sample was prepared for estimation of HOG in SIMS measurements of the hydrogen-charged sample. The gross intensities of hydrogen between the hydrogen-charged sample and the uncharged sample were compared. The gross intensities of hydrogen of the uncharged sample (26.8-74.5cps) were much lower than the minimal gross intensities of hydrogen of the hydrogen-charged sample (462-1140 cps). Thus, we could reduce the H-BG enough to estimate the hydrogen charged into the type 316 L sample. Moreover, we developed a method to determine intensities of H-BG in the measurement of the hydrogen-charged sample by estimating the time-variation of hydrogen intensities in the measurements of the uncharged sample. The intensities of the charged hydrogen can be obtained by subtracting the estimated intensities of the H-BG from the gross intensities of hydrogen of the hydrogen-charged sample. The silicon sputtering method used to reduce H-BG and the determination method for H-BG in this research can be applied to the accurate hydrogen analysis for other various metallic materials.