A resist scattered on and attached to unwanted portions is stably detected. A target inspection region including the unwanted portions to which the scattered resist should not be attached is illuminated with white light to obtain a color image, and a region having the same hue and chroma as a resist is detected. The target inspection region may be illuminated with light containing a first wavelength light exhibiting high reflectance for the unwanted portions and high absorbance for the resist and a second wavelength light exhibiting high reflectance for the unwanted portions and high transmittance for the resist to detect a color image obtained with the second wavelength light from the images of the target inspection region which are obtained by illumination with the illumination light. The resist attached to the unwanted portions may be detected on the basis of the contrast of the image obtained upon illumination with only the first wavelength light. The image of a resist-attached portion is extracted as a portion having lightness not more than a predetermined value from the images of the target inspection region which are obtained by illumination with the first wavelength light, and there is extracted the image of the scattered resist attached to the unwanted portions which are common to both the image of the unwanted portions having no scattered resist thereon, said image being obtained upon illumination of the target inspection region with the second wavelength light, and the image of the resist-attached portions.