PURPOSE: To obtain an apparatus for generating air bubbles wherein a temp. detecting part is easily adjusted and which has a function with high reliability.

CONSTITUTION: The title apparatus is constituted by providing a temp. detecting part detecting a temp. in a main body and transmitting a signal into a control circuit part 6 in the main body 1 corresponding to the upper layer part in the bath and a control circuit part 6 controlling the function in the main body 1 corresponding to the lower layer part in the bath. The control circuit part 6 is not influenced by the temp. of hot water floating up caused by convection to make it possible to make the difference between the upper limiting temp. in a temp. range wherein electric parts of the control circuit 6 work normally and the detecting temp. of the temp. detecting part 7 to be large and the detecting temp. is easily adjusted.