Abstract: This invention aims at casting a large silicon crystal grain-containing ingot (14) by melting a silicon material (20) by scanning the same with an electron beam, and gradually cooling molten silicon (5) thus obtained. A method of casting a crystalline silicon ingot by electron beam melting, involves of the steps of melting a silicon material (20) by scanning the same with an electron beam, cooling the outer lower surface of molten silicon (5) thus produced while increasing the temperature of the molten silicon (5) suitably so as to generate crystals thereof, and gradually precipitating a crystalline silicon ingot (14) by the weight of itself in accordance with the generation of the crystals.