To provide a bath facility, and an operating method of the bath facility provided with both functions as a micro bubble bath and a carbonic acid bath, and capable of realizing the functions by a facility composition comparatively close to a present bath facility.

The bath facility 1 is composed such that a circulation passage 4 is provided for circulating bathtub water w1 between a bathtub 2 interior and a combustion type reheating heating part 3, the bathtub water w1 guided from the bathtub 2 interior to the reheating heating part 3 via an outward passage 5 is heated by the reheating heating part 3, and it is returned to the bathtub 2 interior via a return passage 8. In the outward passage, a temperature of outward water w2 from the bathtub 2 is lowered, gas is dissolved in the outward water w2 in a low temperature state, produced gas dissolved water w3 is pressurized and guided to the reheating heating part 3, and a pressure of the heated gas dissolved water w3 is reduced by a pressure reducing valve 18 to carry out micro-bubbling in the return passage.