An image display apparatus having a three-dimensionally decentered optical path to attain a reduction in overall size of the apparatus and to place constituent members effectively in a dead space, thereby permitting the apparatus to be designed in a variety of ways. The apparatus includes an image display device and a viewing optical system for leading an image formed by the image display device to a pupil. The viewing optical system has at least a first reflecting surface and a second reflecting surface positioned closer to the pupil than the first reflecting surface along the optical path. A first plane defined by the optical axis incident on the first reflecting surface and the optical axis reflected therefrom and a second plane defined by the optical axis incident on the second reflecting surface and the optical axis reflected therefrom intersect each other at an arbitrary angle, thereby forming a three-dimensionally decentered optical path. At least either one of the first and second reflecting surfaces has a curved surface configuration.