PURPOSE: To precisely measure the shapes of vegetables and fruits such as melons, etc., and thus improve the precision and reliability of shape evaluation of vegetables and fruits.

CONSTITUTION: The image which is taken by a camera is taken in (S1) and the image is processed (S2) into multiple signals to obtain an image shown as (B). To evaluate the shapes at the equatorial parts of vegetables and fruits are good or not, the true circular degree (circular shape degree) C1 of the part surrounded with the image elements of the parts having brightness '1' and '2' shown as (C) is calculated (S3). Whether the shapes of the equatorial parts are good or not is judged by comparing the calculated true circular degree C1 with the prescribed value α1 (S4). In the case where the shapes of the equatorial parts are good, the true circular degree C2 of the part (B) surrounded with the slit light is calculated (S5, 6) further to evaluate whether the shapes of the parts to which the slit light is radiated are good or not. Then, whether the shapes are good or not is judged by comparing the calculated true circular degree C2 with the prescribed value α2.