To provide a refining apparatus of material for machining work enabling preparation of the material for machining work at ease, which material can suppress occurrence of cast cavity to the extremely low level and accordingly can be used for manufacturing of a trial product or parts of a small lot by machining, and to provide the refining method and the casting method of the material for machining work.

The refining apparatus 10 of the material for machining work comprises an electric melting furnace 16 to melt the aluminum material 12 for mass-productive molding work and an argon gas feeding unit 18 which continuously blows argon gas 24 into molten metal of the aluminum material 12 in the electric melting furnace 16. Hydrogen gas 14 in the molten metal of the aluminum material 12 can be removed by blowing the argon gas 24. After the argon gas 24 is blown for a designated time, the molten metal of aluminum material 12 is poured into an iron mold and then the material for machining work suitable for the trial product manufacturing having the extremely low level of cast cavity occurrence is obtained by gravity casting.