PURPOSE: A fraction of a mandarin orange leaf extract containing a compound is provided to enable safe long-term administration without side effects and to be used as a pharmaceutical composition for preventing and treating cancer. CONSTITUTION: A pharmaceutical composition for preventing or treating cancer contains a compound selected from a group consisting of 2,4-di-tert-butylphenol, campesterol, and stigmasterol, a pharmaceutically acceptable salt thereof, or a fraction of a mandarin orange extract as an active ingredient. The mandarin orange is Satsuma mandarin. The fraction is a chloroform fraction of a methanol extract of mandarin orange leaves. The cancer is gastric cancer, breast cancer, or cervical cancer.본 발명은 2,4-디-tert-부틸페놀(2,4-Di-tert-butylphenol), 캄페스테롤(campesterol) 및 스티그마스테롤(stigmasterol)로 이루어진 군으로부터 선택되는 화합물, 이의 약학적으로 허용 가능한 염, 또는 상기 화합물을 포함하는 밀감 잎 추출물의 분획물을 유효성분으로 함유하는 암 예방 또는 치료용 약학조성물 및 식품에 관한 것이다.
