L-ribose has recently attracted interest as a starting material for antiviral drug. It could be obtained from Larabinose by epimerization reaction. Epimerization reaction was carried out with molybdenium oxide or molybdic acid catalyst and methanol/water solution. Reaction temperature, methanol percentage, and catalyst kind were selected to find an optimum reaction condition. Ion exhange chromatography was used for separating epimerization reaction mixture, and then HPLC chromatogram of L-ribose fraction obtained to calculate the yield of the reaction. Shodex ion exchange HPLC column(Model SC1011) and Phenomenex Luna NH2 HPLC column were compared to employ a convenient HPLC analysis. It was found that the usage of 20% methanol, 60 ℃, and 40 g/L molybdic acid gives the best reaction condition with a yield of 21%.