To provide a producing method of a semi-solidified billet improving physical properties as the material for semi-solidified casting, with which molten metal held in a crucible can be transformed into the solid-liquid co-existing state after executing the fining of crystal grain and the degassing, and pull-out shaped cavity with an ultrasonic wave horn is not left and the containing of the oxide film and the air caused by leaving of the cavity can be avoided.

In the method for producing the semi-solidified billet 2, with which the oscillation of the ultrasonic wave horn 5 is given to the molten metal 2a under contacting condition of the ultrasonic wave horn 5 with the molten metal 2a held in the crucible 3, while using a cavity preventing means 6 for preventing the leaving of the cavity in the semi-solidified billet 2, the ultrasonic wave horn 5 is separated from the half-solidified billet 2.