A fan includes an impeller including a boss and a plurality of blades; an air guide portion through which an airflow moves from one end to the other end of the air guide portion; and a bell mouth defining a first suction passage inside the bell mouth and defining, together with an inner surface of the air guide portion, a second suction passage outside the bell mouth. Between an upstream end point located in an inlet of the first suction passage and a downstream end point located in an outlet of the first suction passage of the bell mouth, the bell mouth includes a minimum possible radius point to which a distance, in a radial direction, from a rotation axis of the boss is smaller than a distance, in the radial direction, from the rotation axis to the downstream end point.