An upstream space forming portion of a centrifugal blower has a space division portion that divides an upstream space into an inner connection space and an outer connection space. The outer connection space has an overlapping space that overlaps the space division portion in an axial direction, and a non-overlapping space excluding the overlapping space from the outer connection space. A suction port has an outer overlapping portion located outside the separation cylinder in a radial direction, and an outer non-overlapping portion excluding the outer overlapping portion from the separation cylinder located outside in the radial direction. A relationship S1/S2≥0.5 is satisfied when a first area S1 is defined by projecting a boundary between the overlapping space and the non-overlapping space in the radial direction, and a second area S2 is defined by projecting the outer overlapping portion in the axial direction.