There are provided an image acquisition system capable of storing high-accuracy measurement of changes in the shape of a plant growing process in image information with high accuracy and an analyzing method for analyzing an acquired image to analyze plant growing.There is provided a plant growing analyzing system having operation detection means of a conveying mechanism of a plant in order that an observed plant in an image is photographed at a constantly fixed position or angle; a position detecting mark in the acquired image; a computation part for evaluating detected data to control a conveying amount; and a conveying control part, wherein the growing process of many plants is stored in image information in a long period, and the stored image is used to realize high-accuracy measurement.