<；P>；PROBLEM TO BE SOLVED: To provide a siphon device facilitated in formation of a siphon structure in a simple construction, and structured so as to enable maintenance of the inside of a water flow tube, and to provide an automatic watering device. <；P>；SOLUTION: The siphon device 1 includes: a water flow tube 3 sequentially provided with an inflow port 5, a first upward water path 10, a first over-levee part 7, a first downward water path 11, a first submerged-levee part 8, a second upward water path 24, a second over-levee part 9, a second downward water path 12 and a drainage port 6； and an air vent tube 4 mounted in the water flow tube 3. The siphon device has the following structure: the drainage port 6 of the water flow tube 3 is arranged at a position lower than the inflow port 5； the second over-levee part 9 of the water flow tube 3 is arranged at a position having almost the same height as that of the first over-levee part 7； a water-conducting hole 17 is formed at the air vent tube 4 at a position ranging from the first submerged-levee part 8 to the second over-levee part 9 of the water flow tube 3 so as to make a syphon structure S； the water flow tube 3 and the air vent tube 4 are formed of flexible tubes； and the water flow tube 3 is fixed into the shape of the syphon structure S via fixing members. <；P>；COPYRIGHT: (C)2010,JPO&INPIT
