PROBLEM TO BE SOLVED: To provide a falling detecting device capable of accurately and steadily detecting the falling of a rolled material and surely determining the quality of the rolled material in a material passing state, when strip steel is manufactured by rolling mills.SOLUTION: A falling detecting device 10 is arranged in rolling equipment 1 including rolling mills 6 and a torsion device 8 which is arranged on an outgoing side of the rolling mill 6, rotates a rolled material W, and sends it to the next rolling mill 6. The falling detecting device 10 detects falling of the rotated rolled material W. The rolled material W has a contour shape which has a substantially elliptical cross section and at least one or more curvature peak points X' where a curvature k of the outer peripheral surface of the rolled material W becomes peak. The falling detecting device 10 has: profile measurement means 11 for measuring the profile shape of the rolled material W at the outgoing side of the torsion device 8; feature point calculation means 12 for acquiring an apex X and the curvature peak point X' of the profile shape on the basis of the profile shape; and determination means 13 for determining that the rolled material W falls, when the difference between the apex X and the curvature peak point X' is larger than a threshold value.
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