CENTRIFUGAL BLOWER, BLOWING DEVICE, AIR CONDITIONER, AND REFRIGERATION CYCLE DEVICE

A centrifugal fan includes: a fan including a disk-shaped main plate, and a plurality of blades; and a scroll casing housing the fan, the scroll casing including a discharge portion, and a scroll portion including a side wall, a circumferential wall, and a tongue portion. As compared with a centrifugal fan including a standard circumferential wall having a logarithmic spiral shape in cross-section perpendicular to the rotational shaft of the fan, in the circumferential wall, at a first end being a boundary between the circumferential wall and the tongue portion, and at a second end being a boundary between the circumferential wall and the discharge portion, a distance L1 between an axis of the rotational shaft and the circumferential wall is equal to a distance L2 between the axis of the rotational shaft and the standard circumferential wall, the distance L1 is greater than or equal to the distance L2 between the first end and the second end of the circumferential wall, the circumferential wall includes a plurality of extended portions between the first end and the second end of the circumferential wall, and the plurality of extended portions include maximum points each having a length being a difference LH between the distance L1 and the distance L2.