The influence of vacuum cooling and modified atmospheric packaging was investigated about browning degree, polyphenoloxidase(PPO) activity and free amino acid of shiitake mushroom. During storage, surface browning was inhibited by precooling. PPO activities of shiitake mushroom was increased during storage. Especially, PPO activity was rapidly increased as surface browning was proceeded. And PVC-wrapped mushroom was lower than carton boxpacked mushroom in the changes of surface browning and PPO activity. Total free amino acid contents of shiitake mushroom was 2,510 ㎎% at harvest, but free amino acid content of shiitake mushroom decreased consistantly during storage. Precooled mushroom had more free amino acid content than non-precooled and their contents were fluctuated by storage temperature, packaging methods and storage periods.