A multi-blade centrifugal fan housed in a casing (3) of a centrifugal fan and sucking air from one end in an axial direction and blowing out the air toward the outside in the diametrical direction, the multi-blade centrifugal fan having: a large number of blades (21) arranged around a shaft (11), a side plate (22) connecting the wings (21) at ends (211) at one end in the axial direction, and a main plate (23) connected to the Shaft (11) and connecting the wings (21) at ends (212) at the other end in the axial direction, the side plate (22) being provided with a side plate projection (221, 223) projecting from the wings (21 ), and the side plate protrusion (221, 223) has a balance weight (24) attached for adjusting the balance, the side plate protrusion (221) being an annular first side plate protrusion (221) attached to one End in the axial direction protrudes from the ends (211) of the wings (21) in the axial direction, the locking part (241) is formed on a portion of the balance weight (24) positioned on an inner circumferential surface side of the first side plate projection (221) and a portion of the balance weight (24) positioned on an outer peripheral surface side of the first side plate protrusion (221) closely contacts the outer peripheral surface of the first side plate protrusion (221).
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