PROBLEM TO BE SOLVED: To sterilize and purify a bathroom.SOLUTION: A sterilization water generation device (10) generates sterilization water in a treatment tank (11). The sterilization water is supplied, by being sprayed in mist, from a mist nozzle (60a) to a bathroom through a sterilization water supply passage (98). The sterilization water spreads over the bathroom to sterilize and purify the wall surface and ceiling of the bathroom.