Firearms identification requires professional knowledges and a lot of time cost. It is also necessary to quantitatively evaluate the performance of firearms identification schema. As the first step, the segments of the firing pin impression and primer cap in the cartridge cases may be assumed as one of the promising features for it. In this study, primer caps and firing pin impressions in the cartridge cases are detected by a proposed method utilizing the Hough transforms. From the depth images converted from a three dimensional profile of cartridge cases captured by a confocal microscope, through binarization and the Hough transform followed by the least squared fitting, the primer cap and the firing pin impression are detected by use of aggregation of multiple circles. The experiments using many profiles show the effectiveness of the proposed method, where the average deviation became less than the one by human operators.