PURPOSE: An anticancer composition containing Hylocereus undatus extract is provided to suppress cancer cell proliferation and to ensure anticancer efficiency. CONSTITUTION: An anticancer composition contains Hylocereus undatus extract as an active ingredient. The Hylocereus undatus is isolated from peel or pulp of Hylocereus undatus using water, anhydrous or hydrous low alcohol of 1-4 carbon atoms, acetone, ethyl acetate, butyl acetate, or 1,3-butyelen glycol. The composition is a pharmaceutical composition for preventing or treating cancer or a food composition for relieving cancer. The daily dose of the pharmaceutical composition is 0.001-1000 mg/kg(body weight).