We analyze the origins of major metallic deposits in the Gyeongsang basin by considering the relationship magnetic susceptibility of granitoids and sulfur isotope values. In addition, we determine the distribution appearance by examining the magnetic susceptibility of these granitoids and the sulfur isotope composition of sulfide minerals, in 56 metallic deposits. It appears that high sulfur isotope values of metallic deposits are related to magnetite-series granitoids that were influenced by volcanic rocks of the Yucheon Group, including Fe-Cu-(W-Mo) province at δ³⁴S values 3.7 to 13.3 per mil (av. 7.5‰, n = 4), Cu-Pb-Zn-(Au-Ag) province at δS values -2.7 to 15.7 per mil (av. 4.6‰, n = 154), and Pb-Zn-(Au-Ag-Cu) province at δS values 0.3 to 12.3 per mil (av. 5.3‰, n = 58), Whereas, low sulfur isotope values are related to ilmenite-series granitoids that were influenced by sedimentary rocks in the Hayang Group, including Au-Ag-(Cu-Pb-Zn) province at δ³⁴S values -4.5 to 6.0 per mil (av. 1.7‰, n = 55). We consider the relationship between sulfur isotope values of metallogenic province and magnetic susceptibility of granitoids within the province and show the results on a contour map. The spatial relationship of sulfur isotope composition and granitoid series in the former case indicates that sulfide minerals originated from magnetite-series granitoids consolidated in an oxidizing environment assimilated into the magma during the sinking of oceanic crust. However, it is believed that in the latter case, the isotopic composition of sulfide minerals originated from ilmenite-series granitoids consolidated in a reducing environment of the continental crust influenced by sulfate reduction through bacteria metabolism. Moreover, the southeast area of Gyeongsang basin contains both sedimentary rocks of the Hayang Group and Tertiary volcanic rocks, including Cu-Mo-(Fe-W) province at δ³⁴S values -0.3 to 9.6 per mil (av. 3.7‰, n = 38). Locally, low magnetic susceptibility was observed in the volcanic rocks, although nearby Mujeong metallic deposits at δ³⁴S values 6.2 to 9.6 per mil include rocks of high sulfur isotope composition, which were likely affected by the alteration of magnetite-series granitoids.