the present invention provides a method for inspecting only a contamination which there is a possibility to have an actual influence during exposure on a mask . in this method , a mask comprises at least two areas , each of which has a shade pattern , a first inspection light is introduced to the one face of a first area , a second inspection light to another face of a second area . an image transmitting through the first area and an image reflected by the second area are received and composed to obtain a first composite image . then , an image reflected by the first area and an image transmitting through the second area are received and composed to obtain a second composite image . thereafter , a contamination on the mask is indicated based on the first composite image and the second composite image .