The present invention relates to a technology for using a malate-aspartate shuttle (MAS) inhibitor as an agent for treating cancer. More particularly, provided is a pharmaceutical composition for preventing or treating cancer, containing, as an active ingredient, phenyl succinic acid, methyl malonic acid, N-(1-pyrenyl)maleimide and phthalonic acid, which are MAS inhibitors, or a mixture of the MAS inhibitor and an anticancer drug.
