To provide a leakage flux flaw detecting device for performing defect detection with a satisfactory signal-to-noise ratio even when a ferromagnetic metal body to be inspected is traveling.
A magnetic sensor 6a is provided in the vicinity of the location of the center of a magnetizer 5, capable of moving over a rail 10 for sensor movement according to the moving speed V of a steel plate, and detects leakage flux under an intensively magnetizing condition at an appropriate location. A magnetic sensor 6b is provided at a location separated and upstream from the location of the center of the magnetizer 5 and detects leakage flux under a weakly magnetizing condition. By computing two signals of them, it is possible to cancel a noise component commonly contained in them and perform defect detection with a satisfactory signal-to-noise ratio.
KATO HIROHARU
NAGAMUNE AKIO
