A cross flow fan achieves low power input and low noise level by preventing flow separation on an air inlet side and reducing a maximum air velocity in the gap between the blades. At least one of units constituting a cross flow fan is an appearance unit configured such that when the unit is sequentially cut in a direction from one of rings to the other ring along a plane whose normal coincides with a rotation axis, a region S and a region C appear, the radius of a second circle, serving as an inner circumferencial circle (having a radius), in the region S being a first radius of predetermined length, the radius of the second circle, serving as the inner circumferencial circle, in the region C being a second radius shorter than the first radius.