LEAK FLUX FLAW DETECTING DEVICE

PROBLEM TO BE SOLVED: To provide a technique capable of satisfactorily detecting both the flaws extending in an axial direction and a flaw extending in a circumferential direction using a single flaw detection system and detecting flaws at high speed, without contacting a magnetic material, in a leakage flux flaw detection device for detecting surface flaws in a columnar or cylindrical magnetic material.SOLUTION: The leakage flux flaw detecting device includes a first magnetizer, having ring-like coils 1a and 1b such that a steel material 4 can pass through their inside for magnetizing the steel product 4 in its center axis direction; a second magnetizer having a plurality of tangential coils 2a-2h between the ring-like coils 1a and 1b, through the coils 2a-2h which the steel product 3 can pass for magnetizing the steel material 4 in its circumferential direction; and a flaw detecting head having a plurality of sensors 3a-3h between the second magnetizer and the steel product 4 for detecting leakage flux from the steel material 4.