It is attempted to estimate potential installed thermal power of direct uses of geothermal energy in Japan by computing extractable heat from only existing thermal springs distributed all over the country, under the presumption that no geothermal well is newly drilled. Since the Japanese enjoy the pleasures of natural baths, direct uses of geothermal energy in Japan are required to coexist with bathing. Then, potential installed thermal power is estimated at 2,797.46 MW under some conditions for coexistence and coprosperity with bathing. However, some disqualifying factors and the average load factor may reduce this value by 530 MW, which will be yet about five times larger than the present thermal energy used of 104.69 MW. The oil saved will be up to 0.35% of national consumption.