The video processor 3 includes an image input unit 32 to which first and second images acquired by the endoscope 2 are input at first and second timings t1 and t2 before and after performing a predetermined action on the subject. The first and second correction images CP1 and CP2 are generated by using the first and second images, and the first and second correction images CP1 and CP2 are first and second, respectively. The image processing unit 34 for generating the first and second corrected images AP1 and AP2 applied to the second image, and the color components in the second corrected images AP1 and AP2 to extract the first and second images. A distribution characteristic value calculation unit 35 for obtaining the distribution characteristic values of the first distribution characteristic value, and an image analysis unit 36 for calculating the degree of change of the second distribution characteristic value with respect to the first distribution characteristic value. ビデオプロセッサ３は、被検体に所定の作用を行う前後の第１及び第２のタイミングt1,t2で内視鏡２により取得された第１及び第２の画像が入力される画像入力部３２と、第１及び第２の補正用画像CP1,CP2を第１及び第２の画像を用いて作成する信号生成部３３と、第１及び第２の補正用画像CP1,CP2をそれぞれ第１及び第２の画像に作用させた第１及び第２の補正後画像AP1,AP2を生成する画像処理部３４と、及び第２の補正後画像AP1,AP2における色成分を抽出して第１及び第２の分布特性値をそれぞれ求める分布特性値算出部３５と、第１の分布特性値に対する第２の分布特性値の変化の度合いを算出する画像解析部３６と、を具備とする。
