A system and a method of detecting a chipping of the rail part of a slider of a thin film magnetic head obtains the image of the object of detection and its boundary coordinates by tracing the boundary of the object of detection from the image. A chipping size is obtained from the coordinates of the points on the boundary, and the presence or absence of chipping is judged from the chipping size, thereby enabling the highly precise detection of a chipping defect generated on the boundary portion of the object of detection using a simple structure.