SELF-TRAVELING FLAW DETECTOR

PROBLEM TO BE SOLVED: To perform a crack inspection of a weld zone between a trough rib and a deck while self-traveling on the lower surface of a steel floor system with its retained thereto by a magnetic force regarding a self-traveling flaw detector.SOLUTION: A flaw inspection robot 14 self-travels on the lower surface of the steel floor system while being retained by an attraction force of a magnet. The self-traveling robot 14 is provided with an ultrasonic flaw detecting part 28 to adjust a position in a car width direction by a rack-and-pinion and sliding mechanisms. The ultrasonic flaw detecting part 28 includes an ultrasonic flaw detecting probe 30, a skiing-like sled 34, and springs 40. The ultrasonic flaw detecting probe 30 and the sled 34 can follow the attitude of a fine sliding of a detecting object surface, and the springs 40 are provided at the moving-directional front/rear and retain the plane contact with the detecting object surface even to either-directional movement. A tip portion 34-1 of the skiing-like sled can climb over a projection such as a weld bead and the like.