Isotope abundance and sensitivity factors were taken into consideration in the inference of Ga⁺ primary ion TOF-SIMS fragment pattern of inorganic compounds. As most elements have isotopes, the isotope abundance in the inference of TOF-SIMS fragment pattern should be considered. In this experiment, Cu metal and its compounds that include isotopes: ⁶³Cu and ⁶⁵Cu in the ratio of 69.2 vs. 30.8, are employed as measuring samples. Further, a sensitivity factor experimentally obtained is attempted to use.