Abstract: A non-contacting measuring method for three dimensional micro pattern in a measuring object is disclosed. Three dimensional micro pattern of the surface of the measuring object is measured using blur of light. For measurement, a mechanism of an optical window with a slit is inserted between light source and the measuring object. The blurred image is captured by charge coupled device sensor based image frame grabber, and is analyzed in personal computers. All the values of the relative height differences are obtained in overall scanning measurement area of the measuring object. The relative height differences are the distances from the reference position to the other positions. The reference position is selected when its image is sharp in focus on the screen. At this time, images of the other positions except the reference position are blurred out of focus on the screen.