PURPOSE: To obtain an apparatus, which can positively detect the surface flaw expressed as a magnetic particle pattern without missing and can perform the surface-flaw detecting work efficiently.

CONSTITUTION: On a moving truck 1, which can move on a material under inspection S, a magnetizing device 2 for magnetic-particle crack detection, a lighting device 3 for lighting the place of the magnetic-particle pattern expressing a surface flaw, a CCD camera 4, which picks up the image of the magnetic-powder pattern, and a 6-inch type liquid-crystal color display 11, which displays the image signal from the camera 4, are provided. The camera 4 is provided so that the optical angle formed by the optical axis and the surface of the material under inspection becomes 60-90 degrees and the magnification of the image of the size of the magnetic-particle pattern on the screen of the display with respect to the actual size of the magnetic-particle pattern on the material under inspection becomes 0.9-1.2. In this way, the image of the magnetic-particle pattern expressing the surface flaw can be sensed with naked eyes by observing the screen even under the state wherein the moving truck 1 is moved on the material under inspection.