An automatic LSI package lead inspection system for backside lead specification is proposed. The proposed system inspects not only lead backside contamination but also the mechanical lead specification such as lead pitch, lead offset and lead overhangs (variations in lead lengths). The total inspection time of a UQFP package with a lead count of 256 is less than the required time of 1 second. Our proposed method is superior to the threshold method used usually, especially for the defect between leads.