Eye fatigue in an observer is reduced in the case in which observation is performed by performing visual comparison between an imaging subject and an auxiliary indication superimposed on the imaging subject in a three-dimensional image. Provided is an image-processing device (2) including a display portion (3) that displays a three-dimensional image reproduced from two parallax images of an imaging subject attention-point detecting portions (4 and 5) that detect an attention point of the observer observing the three-dimensional image a parallax calculating portion (6) that calculates parallax between the two parallax images at the detected attention point an auxiliary-indication creating portion (7) that creates an auxiliary indication to which the same parallax as the parallax calculated by the parallax calculating portion (6) is assigned, that superimposes the created auxiliary indication on the three-dimensional image, and that displays the superimposed image on the display portion (3).
