To provide an automatic liquid stopping device of low cost and high reliability in which device constitution can be formed simply.

A pull-up piece 16 is manually pulled up to let a magnet 29 be magnetically attracted by an iron plate 28 through an elastic film 11, and a sealing valve 27 releases a discharge port 23 and a stopper 24 for feeding liquid. As liquid reaches a liquid surface stopping position in an air pipe 14, air in the air pipe 14 is compressed to extrude air between the elastic film 11 and the iron plate 28, and an elastic body is inflated. It is further inflated to release the magnet 29, and drop the sealing valve 27, thereby an opening part of the stopper 24 is sealed to stop feeding liquid.