The greenhouse temperature controls in general have been managed by the above-ground part environment, But the temperature of root zone was known very important factor for the 9rofth and the yield of vegetables in greenhouse. The purpose of this study is to develop a good method for cultivation using solar energy which can apply warming soil and to develop the greenhouse soil temperature automatic control system. Followings are summary of this study：1 When the greenhouse inner temperature changes were about 24$^{circ}C$ during a day in October, the temperature of non-warmed soil was differenced 6$^{circ}C$ in the depth 10cm and 3$^{circ}C$ in the depth 20cm. 2. When water supply temperature was kept at 40, 50 and 6$0^{circ}C$, the lowest soil temperature in the depth of 10cm is 2$0^{circ}C$ and that of 20cm was 23$^{circ}C$. and when the water supply temperature was over 4$0^{circ}C$, the space heating temperature did not affect the temperature variation of soil. 3. In comparison with conditions of the warmed and non-warmed soil, when the water supply temperature is 28$^{circ}C$, soil temperatures had the high temperature of 4$0^{circ}C$~7$^{circ}C$ in the depth of 10cm to 20 cm. 4. The line of boundary area was appeared in the depth of 15~20cm, 13~19cm and 12~17cm. when the water supply temperature was 4$0^{circ}C$, 5$0^{circ}C$ and 6$0^{circ}C$. 5. When th inner greenhouse air temperature is maintained over 11$^{circ}C$ and the water supply temperature is supported 28$^{circ}C$, the lowest temperature is kept up over 2$0^{circ}C$.