The operation rate of a circuit pattern inspecting apparatus is prevented from deteriorating by measuring image noise of the circuit pattern inspecting apparatus and detecting the sign that the apparatus is to be in an abnormal state. Provided is the circuit pattern inspecting apparatus wherein circuit pattern abnormalities are detected by irradiating a substrate having a circuit pattern formed thereon with an electron beam and detecting generated secondary electrons or reflected electrons. The circuit pattern inspecting apparatus is provided with: an image processing section wherein an image is generated based on the signal intensities of the detected secondary electrons or those of the reflected electrons and the image is displayed for a display apparatus of the interface; and a control section which analyzes the frequency of noise included in the image.