A disclosed centrifugal blower comprises: a centrifugal fan; a scroll casing which is configured so as to surround the centrifugal fan, has an air inlet on at least one surface thereof, has an air outlet on one side thereof, and guides, to the air outlet, air discharged from the centrifugal fan; an expansion part which is provided at the air outlet and is configured such that the cross-sectional area of the flow path is expanded in the air discharge direction; and a dividing plate which is provided in the expansion part, is arranged at the outside of the air outlet and is arranged lengthwise along the flow direction of the air discharged from the air outlet.