Against shortcomings in the prior art and to-be-solved technical problems, the invention provides an instant heating type unit bathroom. A working medium circulation system and a shower room discharge exhaust gas system and a waste water system are coupled, wherein the working medium circulation system and the exhaust gas system are coupled at the position of an exhaust gas evaporator, and the working medium circulation system and the waste water system are coupled at the position of a waste water evaporator. After part of tap water first recycles part of heat of waste water discharged from a bathroom through a preheater, the tap water enters a water supply sleeve type condenser, the tap water is heated through the water supply sleeve type condenser of the working medium circulation system, and water coming out of the water supply sleeve type condenser and another part of unheated tap water are matched under the effect of a mixing water valve to form warm water at a required temperature for shower. The water supply sleeve type condenser has two types which are a snakelike sleeve type heat exchanger and a header sleeve type heat exchanger, and working mediums and water can be selected respectively to flow in an inner pipe or an outer pipe of the sleeve type heat exchanger. Compared with a conventional water supply immersion type condenser, the water supply sleeve type condenser is higher in heat transfer coefficient and better in energy-saving effect, the instant heating type unit bathroom is instantly available, the top layer space height of the unit bathroom is further reduced, the manufacturing cost is reduced, and the unit bathroom has a larger internal activity space for users.