Abstract: Disclosed is a linear pattern recognizing method of recognizing a linear pattern included in the image data stored in an original image memory. The memory region of the original image memory is divided into a plurality of smaller regions, and the image data of the smaller regions are utilized to obtain projection waveforms at a plurality of projection angles for each smaller region. The projection waveforms thus obtained are analyzed to detect the presence or absence, line direction (.theta.), smaller region. According to the results of detection, a linear segment corresponding to the linear pattern is extracted for each smaller region.