PROBLEM TO BE SOLVED: To provide a water supply device supplying a prescribed quantity of water to plants at prescribed time intervals. SOLUTION: This water supply device has a water storage tank 2 storing water, a drainage tank 3 held in the water storing tank 2 so that the outer surface of the bottom side of the drainage tank is soaked in water in the water storage tank 2 in a condition of storing water in the water storage tank 2, and a drainage passage 4 connecting the inside of the drainage tank 3 to the outside of the water storage tank 2. The drainage tank 3 has an inflow part 7 letting water in the water storage tank 2 flow into the drainage tank 3 and a siphon pipe 8 discharging the water flowing into the drainage tank 3 through the drainage passage 4 to the outside of the water storage tank 2. The inflow part 7 is formed on a part soaked in water in the water storage tank 2, on the bottom side of the drainage tank 3. The siphon pipe 8 is set in the drainage tank 3 and the discharging part 10 of the siphon pipe 8 is connected with the inflow part of the drainage passage 4, and the drainage passage 4 is set below the siphon pipe 8. COPYRIGHT: (C)2005,JPO&NCIPI
