The present invention relates to a pharmaceutical composition for preventing or treating cancer, comprising a green younggeum extract, and to a health functional food for preventing or improving cancer. When using a pharmaceutical composition for preventing or treating cancer comprising the extract of Nogyeonggeum according to the present invention as an active ingredient, and a health functional food composition for preventing or improving cancer comprising the extract of Nogyeonggeum as an active ingredient, there are few side effects and specific for cancer cells. It can effectively prevent or treat cancer by inhibiting proliferation, exhibiting antioxidant activity, and regulating the expression of cancer cell death-related genes by inhibiting the citric acid cycle, and thus can be widely used in the pharmaceutical industry and health functional food field.