PROBLEM TO BE SOLVED: To provide a hot water supply port adaptor for a bathtub in which maintenance/inspection and cleaning for a bubble jet nozzle can be easily performed.SOLUTION: A hot water supply port adaptor for a bathtub comprises an adaptor main body disposed to penetrate a bathtub wall part, an in-tank arrangement part 4 disposed in the adaptor main body and disposed in the bathtub, and a bubble jet nozzle 5 provided in the in-tank arrangement part 4 with a jet port 50 at a tip being directed forward, the jet port 50 of the bubble jet nozzle 5 jets microbubble water which is hot water being mixed with microbubble. A nozzle attachment recess 43 is formed in a front face of the in-tank arrangement part 4, and the bubble jet nozzle 5 is attached attachably/detachably in the nozzle attachment recess 43.
