To provide a toilet bowl restrained from being soiled while preventing the wasteful supply of sterilizing water without giving a user an uncomfortable feeling by supplying the sterilizing water, simultaneously with toilet bowl flushing operation and supplying the sterilizing water at the timing when sterilization is effectively performed.

The toilet bowl is provided with: a toilet bowl receiving the user's excrement and formed with a trap for storing standing water, between the toilet bowl and drain piping; a flushing water supply means for supplying the toilet bowl with flushing water; and a sterilizing water supply means for supplying the sterilizing water together with the flushing water. A learning control means is provided for predicting a not-in-use time zone based on the working state in a fixed period of the toilet bowl, and the sterilizing water is supplied for toilet flushing from a predetermined time before the not-in-use time zone until the not-in-use time zone.