To provide a coal-fired boiler plant that can effectively prevent high-temperature corrosion occurring from a molten phase formed by an alkali iron sulfate adhering to the high-temperature region surface inside a boiler device.

In the coal-fired boiler plant including a pulverizing device 4 pulverizing coal, and the boiler device conveying coal particles pulverized by the pulverizing device 4 and firing them by using a burner 7: solid alkali compound-containing solid matter addition means 2 and 22 are connected to a supply system of coal to be supplied to the pulverizing device 4, and an addition amount regulating means 21, which regulates an addition amount of an alkali compound-containing solid matter according to a supply amount of coal to be supplied to the pulverizing device 4, is arranged.