An identification number is carved by laser on a semiconductor bare chip for flip-chip-attach assembly. Each digit of an identification number is represented by the inclination of ID bars that are composed of five short lines. This paper proposes a method to recognize an identification number on a bare chip by image processing. The position and angle of orthogonal standard bars that are used to allocate ID bars are recognized by the combinational Hough transform using differences between edge directions of a pair of edge points. Inclinations of ID bars are measured using statistical distribution of edge directions. All identification numbers on 320 bare chips were recognized successfully, and the processing time recorded 0.37 second by an identification number.