PURPOSE: To provide an apparatus for automatically stopping a hydrant for irrigation to automatically stop the water discharge when the water level of an irrigation channel reaches the optimum level.

CONSTITUTION: This apparatus is composed of a 1st cylinder 1, a linearly movable 1st member 4 slidably inserted into the 1st cylinder to close the inlet opening 2, a 2nd member 12 connected to the 1st member 4 through a connection rod 6, linearly movable against a stress by the force applied by a 1st coil spring 7 in the direction to be separated from the 1st member 4, having an outlet opening 3 and a part 9 having the same diameter, containing a 2nd coil spring 10 in the member and having nearly cylindrical form with a longitudinal groove 11 having two-stepped depth on the side face, a 2nd cylinder 16 perpendicularly attached to the side face of the 1st cylinder 1, inserted into a small hole 13 positioned corresponding to the groove 11 and containing a piston 15 forced with a 3rd coil spring 14 and a water-level detection part 25 having an upswelling port, a rod and a float connected with each other through a pipe 18 and constructed to close the upswelling port with the rod by the lifting of the float.