Effects of gamma irradiation(2.5∼20kGy) on water absorption property was studied for a local variety of black soybeans. In water absorption patterns of black soybeans, the time to reach a fixed moisture content was reduced depending on the increment of water soaking temperature and irradiation dose. Irradiation at 2.5∼10kGy resulted in the reduction of soaking time of black soybeans by about 1∼3 hours and the increase of hydration capacity by 10∼20%, respectively, compared to the nonirradiated control black soybean. The water uptake rate constant of the irradiated black soybean difinitely increased with the increase of dose levels and water soaking temperature. The activation energy for water absorption and z-value were lower in the irradiated black soybeans than in the nonirradiated control black soybean. The efficacy of water absorption property in the irradiated black soybeans was also recognized after one year of storage at room temperature.