PURPOSE: To inspect a resist film pattern, etc. easily and exactly, and to improve yield of manufacture of a semiconductor device, by scanning a body to be inspected, by moving an optical beam, detecting the light which is irregularly reflected and radiated by the body to be inspected, by a dark view field, and processing its output signal.

CONSTITUTION: An optical beam emitted from a laser 1 is made incident to the first optical deflecting element 5, executes scanning in the X direction, subsequently, is made incident to the second light polarizing device, and executes scanning in the Y direction. After that, the optical beam divided into two by a beam splitter for comparison and decision is made incident to objective lenses 14, 15, respectively. The laser beam focused to the edge part of a wafer 17 and a resist film 24 is irregularly reflected by its boundary part, passes through optical fibers 28, 27, is made incident to photoelectric converting elements 25, 28, and generates an edge signal. The edge output signal is supplied to a defect deciding circuit 45 through amplifiers 42, 43, and both input signals are added, are made to pass through a slicer 46, and after that, are supplied to a defect detecting and processing circuit 47, and are processed.