There is provided an electron beam detector including an electron beam scatterer which is disposed at a predetermined distance below a shield including a plurality of openings formed therein, and a beam detection element disposed at a predetermined distance below the scatterer and configured to convert an electron beam into an electric signal. In the electron beam detector, the scatterer is disposed at an equal distance from any of the openings in the shield, and the beam detection element is disposed at an equal distance from any of the openings in the shield. Thus, the electron beam detector can suppress a variation in detection sensitivity depending on the position of the opening.