An electron beam processing device includes a chamber housing that defines a chamber interior space and has a first opening. A carriage is movable along the first opening. An electron beam generator is disposed on the carriage so that the generated electron beam passes through the first opening when the carriage moves along the first opening. A disk is disposed between the chamber housing and the carriage and is rotatable about a rotational axis, which is perpendicular to the first opening, at least between a first rotational position and a second rotational position. The disk has a second opening spaced from the rotational axis of the disk in the radial direction. The rotational axis of the disk is disposed so that the first opening always overlaps the second opening at least along an electron beam propagation axis when the disk rotates between the first and second rotational positions.