An electron beam melting furnace includes a hearth, a mold, an electron gun for keeping metal as a molten state, an electron beam controller for controlling direction of the electron beam, an image sensor for molten metal, and an operating device. A method for operating the furnace includes a step of inputting electron beam emitting coordinates in the electron beam controller, a step of emitting the electron beam, a step of detecting a high electron beam intensity spot by the image sensor, a step of calculating coordinates of high electron beam intensity based on the detected signal by the operating device, a step of calculating differences between the coordinates of emission and the coordinates of high electron beam intensity spot, a step of inputting the difference in the electron beam controller, and a step of controlling the location of electron beam spot.