To provide a sterilizing device for a toilet stool which is provided with a function capable of preventing scale and slime from clinging to a flush toilet stool and odor from generating, and also preventing silver or silver chloride forming black stains on the bowl surface of the flushing toilet from generating.

In a sterilizing device installed in a flushing water supply pipe line for a toilet stool to a flushing toilet, at least one of at least a pair of disinfectant supply parts supplying a disinfectant component to the flushing water for the toilet stool is a metallic electrode eluting silver ion. Further, a means mixing and accelerating water flow of the surface of the silver electrodes is provided. In this way, generation of metal silver or silver chloride bringing black stains on the bowl surface can be prevented, and silver ion cleaning water bringing less metal silver or silver chloride can be supplied to the toilet stool.