The powder classifying apparatus classifies raw material powder having a particle size distribution into fine powder and coarse powder and includes a disk-like centrifuge chamber formed as a space between two facing members, a plurality of air nozzles for supplying gas into the centrifuge chamber to generate a whirling stream, a raw material ejecting nozzle for supplying the raw material powder to the whirling stream generated in the centrifuge chamber, a fine powder collecting tube disposed in a central portion of one of the two facing members and communicating with the centrifuge chamber to discharge the gas including the fine powder separated in the centrifuge chamber to the outside, a cylindrical first wall disposed at an opening portion formed of the fine powder collecting tube, and a cylindrical second wall disposed on the other one of the two facing members and facing the first wall with a given interval.