PROBLEM TO BE SOLVED: To provide a toilet apparatus capable of efficiently decomposing organic matters.SOLUTION: A toilet apparatus includes a light source device 310 that applies ultraviolet rays to a bowl part 801 that is provided in a toilet bowl 800 and in which a photocatalytic film 803 is formed. The light source device 310 performs a first irradiation mode of applying the ultraviolet rays with an irradiation intensity of 100 microwatt/square centimeter or more to at least any part of the bowl part 801.