To provide a biomass fuel combustion device free from accumulation of ash in a combustion chamber and dispensing with ash discharging work.

This biomass fuel combustion device comprises a fuel supply means 3 for supplying biomass fuel to the combustion chamber 13 provided with a combustion burner 9 in a powder-particle state, a peripheral wall nozzle 17 for supplying the combustion air from an inner peripheral wall of the combustion chamber 13 as swirl flow, a bottom portion nozzle 18 for supplying the combustion air toward a bottom portion of the combustion chamber 13 as swirl flow of the direction same as the swirl flow, and an induction discharging means for inducting and discharging the combustion air with ash at the neighborhood of a top portion of the combustion chamber 13.