To suppress unevenness in in-furnace temperature due to difference in combustion characteristics and the like between coal and biomass, in a comminution system for supplying the coal and biomass as fuel.

As this comminution system has a vertical comminution machine exclusively used for the biomass, a vertical comminution machine for the coal is not affected even when the vertical comminution machine exclusively used for the biomass runs into trouble and stops, and it becomes unnecessary to stop a combustion device. Further as a mixing ratio of the biomass to the coal can be freely changed, and the coal and the biomass are burned in the same burner, unevenness in the in-furnace temperature of the combustion device can be suppressed, and efficiency of a boiler can be kept.