AR is a display technology of MR. AR is used to augment the human ability to process real world information by adding computer-generated virtual information. A HMD type MF (multi-focus) 3D display is developed for an application to AR and experiment about satisfaction of eye accommodation is tested. Four LEDs and a DMD are used to generate four parallax images for single eye and the displayed MF image is added to actual real world view. The MF means the ability of monocular depth cue to various depth levels which are represented in 3D image displayed on 3D display system. By achieving MF function, we developed a 3D display system for only one eye, which can satisfy the accommodation to displayed virtual objects at various depths. Therefore this proposed 3D display system has a possibility for solving the problem that the 3-dimensional image display system using only binocular disparity can induce the eye fatigue caused by the mismatch between accommodation of each eye and convergence of two eyes. Additionally, the HMD type MF 3D display can be applied to a monocular 3D display and monocular AR 3D display.