The investigation was aimed to reduce the period of bed log through the protection of harmful fungi and to know the effects of physiological activating substances on the yield increase of Lentinus edodes. Mycelial growth was evaluated both the bed logs and physiological activating substances, respectively. I percent extract of Allium cepa and malt as a physiological activating substance was highly effective in mycelial growth of Lentinus edodes. Better effects among the bed logs by the application fo physiological activating substances observed in both Quercus serrata and Carpinus laxiflora. This results suggested that supplement of physiological activating substances to the bed log would be beneficial for the production of Lentinus edodes.