To improve the ability to retrieve a taken image of an internal body and to easily recognize the organ depicted in each image, an average color bar 507 indicating the overall imaging period of images taken in time sequence by an capsule endoscope is displayed, a movable slider S is shown on the average color bar 507, an image at the imaging time corresponding to the position of the slider S is displayed and an average color based on taken image data is displayed at the time-associated position on the average color bar 507.
