To improve selection accuracy of a fruit whose shape is abnormal and on whose surface there is irregularity, without complicating a structure of a conveyor device.SOLUTION: The invention is configured to separate a line 7 extracted from image data 6, by a predetermined equal interval Df determined by experiment to a fruit F being directed to a front surface, determine an angle of the line 7 on a point Pi for every interval Df, and then calculate an irregularity degree Cf for setting for front surface, by counting a number in which an absolute value of an angle difference between adjacent points Pi exceeds a predetermined angle difference threshold by experiment to the fruit F being directed to a front surface. Then, an irregularity degree Cr for setting for a rear surface is calculated, by a way similar to a way for determining the irregularity degree Cf for setting for a front surface. Then, the Cr is converted into a correction irregularity degree Cr' for setting for a rear surface by a predetermined conversion formula determined by experiment so that distribution of Cr becomes a same scale to a scale of the Cf distribution, and then, out of the Cf and Cr', larger one is determined as the irregularity degree. When the irregularity degree is equal to or more than a predetermined irregularity degree threshold being determined by experiment, a fruit 1 is determined as a fruit whose shape is abnormal.SELECTED DRAWING: Figure 4
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