A plasma disinfection device of an embodiment includes: an electrical dust collector including a plurality of heat exchange fins, a needle electrode which causes a discharge in a gas flow flowing between the plurality of heat exchange fins, and a direct-current power supply electrically connected to the needle electrode; and a plasma generator including a dielectric provided on each of facing surfaces of the plurality of heat exchange fins, a discharge electrode provided to be exposed on a surface of the dielectric and arranged to cross a direction of flow of the gas flow, and an alternating-current power supply electrically connected to the discharge electrode.