A sirocco fan including: a scroll; a fan body that is rotatably disposed in the scroll and includes a plurality of blades arranged in a cylindrical manner; and a motor for rotationally driving the fan body, wherein a center of a bell mouth that forms a suction opening of the scroll conforms to the rotation center of the fan, the scroll includes two straight line portions (12,13) approximately in parallel with each other on a whorl-like outer shape thereof, and characterising in that an intersecting point of a parallel line, which is in parallel with the two straight line portions (12,13) and passes through a center O of a bell mouth, and an outer shape of the scroll is defined as a point A, a point on the outer shape of the scroll, at which a distance between the outer shape of the scroll and a rotation center P of a fan is maximum, is defined as a point B, intersecting points of a line, which is perpendicular to the straight line portions (12,13) and passes through the rotation center P of the fan, and the straight line portions (12,13) are defined as a point C and a point G, respectively, a fan radius is defined as R, and an angle formed by a segment OA and a segment OB is defined as θ, the following formulas are satisfied: (OB-R)/R ≥ 0.475, 0.3 ≤ (OC-R)/R ≤ 0.45, θ ≤ 70°, and OB ≥ OC, wherein a rib taking a form of a substantially rectangular parallelepiped shape is provided at each of both ends of a tongue portion of the scroll, and that a following formula is satisfied: segment XY ≤ segment XZ, where a point in the rib most apart from the fan body is defined as a point X, a point in a circular arc portion of the tongue portion most apart from the fan body is defined as a point Y, and a point in the rib nearest to the fan body is defined as a point Z. a scroll; a fan body that is rotatably disposed in the scroll and includes a plurality of blades arranged in a cylindrical manner; and a motor for rotationally driving the fan body, wherein a center of a bell mouth that forms a suction opening of the scroll conforms to the rotation center of the fan, the scroll includes two straight line portions (12,13) approximately in parallel with each other on a whorl-like outer shape thereof, and characterising in that an intersecting point of a parallel line, which is in parallel with the two straight line portions (12,13) and passes through a center O of a bell mouth, and an outer shape of the scroll is defined as a point A, a point on the outer shape of the scroll, at which a distance between the outer shape of the scroll and a rotation center P of a fan is maximum, is defined as a point B, intersecting points of a line, which is perpendicular to the straight line portions (12,13) and passes through the rotation center P of the fan, and the straight line portions (12,13) are defined as a point C and a point G, respectively, a fan radius is defined as R, and an angle formed by a segment OA and a segment OB is defined as θ, the following formulas are satisfied: (OB-R)/R ≥ 0.475, 0.3 ≤ (OC-R)/R ≤ 0.45, θ ≤ 70°, and OB ≥ OC, wherein a rib taking a form of a substantially rectangular parallelepiped shape is provided at each of both ends of a tongue portion of the scroll, and that a following formula is satisfied: segment XY ≤ segment XZ, where a point in the rib most apart from the fan body is defined as a point X, a point in a circular arc portion of the tongue portion most apart from the fan body is defined as a point Y, and a point in the rib nearest to the fan body is defined as a point Z.