A biomass-mixed, pulverized coal-fired burner, comprising: a biomass fuel jet nozzle that supplies biomass fuel conveyed by biomass fuel primary air as a biomass fuel stream; a fuel jet nozzle including a fuel conveying pipe that introduces pulverized coal fuel conveyed by pulverized coal fuel primary air as a pulverized coal fuel stream to thereby form a flow path for the pulverized coal fuel stream, and a fuel jet port through which the pulverized coal fuel stream is jetted together with the biomass fuel supplied inside of the fuel conveying pipe from the biomass fuel jet nozzle; a secondary air nozzle having a secondary air jet port that surrounds an opening in the fuel jet port, the secondary air jet port jetting a secondary air swirl flow; and a tertiary air nozzle having a tertiary air jet port that surrounds the secondary air jet port, the tertiary air jet port jetting a tertiary air swirl flow, wherein the biomass fuel jet nozzle has a biomass fuel jet port that supplies the biomass fuel into an inside of the fuel conveying pipe included in the fuel jet nozzle, the fuel jet nozzle includes: a fuel swirl vane disposed inside the fuel conveying pipe, the fuel swirl vane configured to change a fuel stream as a mixture of the pulverized coal fuel stream and the biomass fuel stream into a whirling swirl flow such that a pulverized coal fuel component in the fuel stream is distributed with a higher concentration on an outer circumferential wall side of the fuel conveying pipe and a biomass fuel component in the fuel stream is distributed inside of the pulverized coal fuel component; a flame stabilizer disposed at a pipe end of the fuel jet port, the flame stabilizer opening in a funnel shape; and a fuel baffle plate disposed on a pipe inner wall at a position upstream of the flame stabilizer, the fuel baffle plate restricting a swirl of the fuel stream jetted from the fuel jet port, the flame stabilizer has a funnel-shaped widening ring comprising a micro step formed at an intermediate portion thereof, the fuel stream jetted from the fuel jet port is formed so that the pulverized coal fuel stream envelopes the biomass fuel stream, and the secondary air jetted from the secondary air jet port forms a buffer stream between the fuel stream and the tertiary air swirl flow. a biomass fuel jet nozzle that supplies biomass fuel conveyed by biomass fuel primary air as a biomass fuel stream; a fuel jet nozzle including a fuel conveying pipe that introduces pulverized coal fuel conveyed by pulverized coal fuel primary air as a pulverized coal fuel stream to thereby form a flow path for the pulverized coal fuel stream, and a fuel jet port through which the pulverized coal fuel stream is jetted together with the biomass fuel supplied inside of the fuel conveying pipe from the biomass fuel jet nozzle; a fuel conveying pipe that introduces pulverized coal fuel conveyed by pulverized coal fuel primary air as a pulverized coal fuel stream to thereby form a flow path for the pulverized coal fuel stream, and a fuel jet port through which the pulverized coal fuel stream is jetted together with the biomass fuel supplied inside of the fuel conveying pipe from the biomass fuel jet nozzle; a secondary air nozzle having a secondary air jet port that surrounds an opening in the fuel jet port, the secondary air jet port jetting a secondary air swirl flow; and a tertiary air nozzle having a tertiary air jet port that surrounds the secondary air jet port, the tertiary air jet port jetting a tertiary air swirl flow, wherein the biomass fuel jet nozzle has a biomass fuel jet port that supplies the biomass fuel into an inside of the fuel conveying pipe included in the fuel jet nozzle, the fuel jet nozzle includes: a fuel swirl vane disposed inside the fuel conveying pipe, the fuel swirl vane configured to change a fuel stream as a mixture of the pulverized coal fuel stream and the biomass fuel stream into a whirling swirl flow such that a pulverized coal fuel component in the fuel stream is distributed with a higher concentration on an outer circumferential wall side of the fuel conveying pipe and a biomass fuel component in the fuel stream is distributed inside of the pulverized coal fuel component; a flame stabilizer disposed at a pipe end of the fuel jet port, the flame stabilizer opening in a funnel shape; and a fuel baffle plate disposed on a pipe inner wall at a position upstream of the flame stabilizer, the fuel baffle plate restricting a swirl of the fuel stream jetted from the fuel jet port, the flame stabilizer has a funnel-shaped widening ring comprising a micro step formed at an intermediate portion thereof, the fuel stream jetted from the fuel jet port is formed so that the pulverized coal fuel stream envelopes the biomass fuel stream, and the secondary air jetted from the secondary air jet port forms a buffer stream between the fuel stream and the tertiary air swirl flow.