PURPOSE: To enable to recover fluid pressure without losing the kinetic energy of fluid flow, by converting the dynamic pressure possessed by the fluid flow at outlet ports of an impeller into pressure in fluid passages extended between the outlet ports of the impeller and an outlet port of a fan.

CONSTITUTION: Air carried to inlet ports 21 of a fan is passed through air passages 14a separated by guide vanes 17a, 17b. Here, since arrangement is such that these air passages 14a are formed in diverged passages, the depth of which is increased gradually from the inlet ports 21 to an outlet port 22 of the fan, the velocity of air flow is decreased gradually toward the outlet port 22, so that the velocity energy possessed by the air is converted into the static energy corresponding to the drop of the dynamic pressure. Therefore, air introduced from the inlet ports 21 can be discharged to the outside from the outlet port 22 of the fan while recovering pressure without losing almost no velocity energy of the air flow.