Effect of trehalose for the mycelial growth of Tricholoma matsutake were examined. When T. matsutake Z-1 strain was cultured in the partially modified matsutake liquid (PMML) medium and the Hamada matsutake liquid (HML) medium supplemented with trehalose at 24 ℃ for 80days, the vegetative mycelial dry weights showed higher value compared with those of PMML medium and HML medium supplemented with glucose (control). The range of the effect of 1.0-8.0% carbohydrate substrate on vegetative mycelial growth was investigated. The optimal concentration for mycelial growth was 2.0% for the glucose medium but 8.0% for the trehalose medium. To evaluate the potential of the production of trehalase from T. matsutake, the extracellular trehalase activity during the vegetative mycelial growth was measured. The activity of the extracellular trehalase increased during vegetative mycelial growth of T. matsutake and was maximal 70 days after inoculation. This extracellular enzyme was investigated for the purification and the characterization. The partially purified trehalase was obtained from about 1.53l static culture filtrate, with 19.1% recovery, and about 2,940 fold purification. The molecular mass was about 62.6kDa (SDS-PAGE) and 70kDa (Gel-filtration). The enzyme was most active around 40℃ and pH 5.0 and stable over a pH of 4.5~ 6.5 for 30min at 37℃. The enzyme readily hydrolyzed trehalose having α -1,1 glucosidic bond. However, it did not hydrolyze disaccharides such as maltose, iso-maltose, cellobiose, saccharose and lactose.