PURPOSE: To obtain an image display device such as a head-mounted type image display device, etc., capable of clearly observing at a wide viewing angle, besides, capable of reducing the fatigue, because the device is made extremely small in size and light in weight.

CONSTITUTION: The device is constituted of an image display element 6 and an eyepiece optical system 7, the eyepiece optical system 7 is provided with a 1st plane 3, a 2nd plane 4 and a 3rd plane 5 from the side of observer's eyeball 1, a space formed between the 1st plane 3 and the 2nd plane 4 and a space formed between the 2nd plane 4 and the 3rd plane 5 are filled with medium whose refractive index is >1, the curvature of the 1st plane 3 is made differ from the curvature of the 2nd plane 4, the 2nd plane 4 is eccentrically arranged with respect to the visual line 2 of the observer, and the plane 4 is a reflective, or semi-transmissive plane having a concave surface facing to the observer's eyeball 1, and light emitted from the image display element 6 is reflected only by the 2nd plane 4 once without forming an intermediate image, the light from the image display element 6 is refracted by the 3rd plane 5, reflected by the 2nd plane 4 and furthermore refracted by the 1st plane 3, then, the light is made incident on the observer's eyeball 1.