1. A method for inspecting a pattern formed on a substrate, comprising the steps of: moving a table along a first direction on which a substrate to be inspected is mounted; irradiating a converged electron beam on the substrate by scanning the converged electron beam along a second direction which is perpendicular to the first direction; detecting an electron radiated from the substrate by the irradiation of the converged electron beam in which the movement of the table and the scanning of the converged electron beam is synchronized; forming a digital image of the substrate from the detected electron; improving a quality of the digital image by filtering the compensated digital image; and detecting a defect of a pattern formed on the substrate by using the improved quality digital image.