Helium is the most frequently used carrier gas for GC/MS, which is the official standardized test method in Japan to assess chemical substances in indoor air. However, recent global challenges in the supply chain for helium have led to a need to validate GC/MS using alternative carrier gases. In this study, we examined the applicability of hydrogen and nitrogen as helium-alternative carrier gases in the standardized GC/MS analytical test method for volatile organic compounds (VOC) and phthalate esters in indoor air. Comparison of the signal-to-noise ratios of standard solutions showed that detection sensitivities of hydrogen and nitrogen analysis were enough for the standard test method, although these gases, especially nitrogen, were less sensitive than helium. Measurements using these alternative carrier gases showed good linearity and could quantify around 1/100^th of Japanese guideline values for indoor air concentrations. Therefore, hydrogen and nitrogen gases can be applied to the standard GC/MS analysis test method for VOC and phthalate esters in indoor air as alternative carrier gases to helium.