Quantitaties of flavonoids were determined by HPLC in three different ethanol extract (50, 70 and 95%, v/v) from Korean cherry. Antimicrobial activity of the ethanol extract and its solvent fraction (ethyl acetate and n-butanol fractions) against Staphylococcus aureus (ATCC 6538) and Staphylococcus epidermidis (ATCC 12228) was evaluated using MIC and disk test. Additionally, UV protective effect was also determined. The highest flavonoid quantity was found in 70% ethanol extract of Korean cherry. The quantities of quercitrin were 12.7 mg% and 2.1 mg% in ethyl acetate fraction and in buthanol fraction, respectively. In addition, the flavonoid in 70% (v/v) ethanol extract of Korean cherry included 14.9 mg% of quercitrin, 6.0 mg% of tannic acid and 5.2 mg% of catechin. Therefore, it was confirmed that main flavonoid of Korean cherry was quercitrin. For antimicrobial activity of ethanol extract of Korean cherry against Staphylococcus aureus (ATCC 6538) and Staphylococcus epidemidis (ATCC 12228), MIC and disk test using ethyl acetate fraction and butanol fraction were carried out. As a result, ethyl acetate fraction with higher quantity of flavonoid showed higher antimicrobial activity. Therefore, it was confirmed that the higher antimicrobial activity was brought about by flavonoid in Korean cherry. For UV protective effect of Korean cherry, ethanol extract showed the absorption zone of ultraviolet rays in 210∼380 nm including 290∼320 nm that is the wave length of UV-B harmful to the skin of human body. The pattern is the same as the absorption zone of 220∼300 nm in catechin and 210∼400 nm in quercitrin. Then, the functionalities of catechin and quercitrin were anticipated. It is expected that quercitrin in Korean cherry has the antimicrobial effect and UV protective effect related to the skin.