Optical system for head mounted display

An optical system for a head mount display is provided to correct both a spherical aberration and a color aberration by using a magnification lens system having an aspherical plastic lens and a diffraction optical element. An optical system for a head mount display includes a micro display device(10), an aspherical lens(20), and a diffraction optical element(30). The micro display device provides an image display function. The aspherical lens is arranged in front of the micro display device and refracts a display beam from the micro display device to provide a magnified screen. The diffraction optical element is arranged between the micro display device and the aspherical lens and diffracts the display beam. The diffraction optical element includes plural groove patterns, which are repeatedly formed on a surface of the aspherical lens, which faces the micro display device.