Abstract: Problem To provide a method for manufacturing silica glass and device for manufacturing silica glass that facilitates the simple manufacture of a highly pure, bubble-free large flat-plate silica glass ingot in a short time. Solving Means In a method for manufacturing silica glass in which a silica glass powder is dropped from a powder supply device above a rotating furnace and layered in a centre portion of a furnace bottom, and then heat-fused and expanded in an outer circumferential direction of the furnace to form an ingot, the drop position and a fusion position of the silica glass powder is dispersed in the bottom portion of the furnace. The drop position of the silica glass powder is displaced from the centre portion of the bottom portion of the furnace, and the silica glass powder is preferably dispersed in the bottom portion of the furnace by the rotational movement of one or both of the powder supply device and the bottom portion of the furnace.