An inspecting method comprises the following steps. A plurality of defect inspection devices is formed on a wafer. Each defect inspection device comprises an insulating layer and a conductive layer stacked over the insulating layer. A defect inspection parameter is set and the wafer is scanned with an electron beam to obtain a plurality of defect signals. The number of defect signals is checked to determine if it is equal to the number of defect inspection devices. If the number of defect signals is smaller than the number of defect inspection devices, the defect inspection parameter is readjusted and the aforementioned step of performing an electron beam scanning and checking for equality between the number of defect signals and the number of defect inspection devices are repeated. The process is complete when the number of defect signals is at least equal to the number of defect inspection devices.