A centrifugal blower has: an impeller; and a casing that houses the impeller. The impeller has: a bottom plate; blades provided on a same circumference of the bottom plate; and a shroud that has the blades interposed between it and the bottom plate, disposed concentric with the bottom plate, and connects end sections of the respective blades. The shroud has: an inclined section that comes closer to the bottom plate moving from a radial direction inside to a radial direction outside; and a shroud side barrier that rises from a position on the radial direction outside of the inclined section towards a side opposite to the bottom plate. The casing has a bell-mouth that opens from a radial direction inside of the shroud to a radial direction outside, and a casing side barrier that projects to an area between the inner periphery of the shroud and the shroud side barrier.