An inspecting method and device for inspecting an object or objects such as photomasks having a plurality of identical patterns, to detect defects of the patterns, wherein the object is placed such that the patterns lie in the same plane, and an inspection mask having a plurality of translucent apertures is placed such that the inspection mask is adjacent and parallel to the object. The inspection mask and the object are moved relative to each other whereby each aperture is positioned opposite to mutually corresponding portions of the patterns. The object and inspection mask are irradiated with rays of light emitted in a direction substantially normal to the plane of relative movements thereof. The rays of light transmitted through the apertures and the object are converted into electric signals, and the electric signals associated with the corresponding portions of the patterns are compared with each other, prior to obtaining the electric signals of all of the plurality of patterns. If the electric signals of the corresponding portions of the patterns differ from each other, these portions are determined to be defective.