The present invention provides a pulverizing screw, a pulverizing casing and a pulverizer having the same. The pulverizing screw includes a rotating shaft and a drive blade which extends from the rotating shaft in a spiral shape. The drive blade rotates in the pulverizing casing in such a manner as to maintain a predetermined distance between the drive blade and the inner surface of the pulverizing casing to prevent the drive blade from being impeded by the inner surface of the pulverizing casing. The drive blade extends from a first end of the rotating shaft in a spiral shape surrounding the rotating shaft in a clockwise or counterclockwise direction and is connected to a second end of the rotating shaft. The pulverizing casing comprises a spherical body having a space therein. The pulverizing screw is installed in the spherical body so as to be rotatable.