Disclosed herein is an optical position adjustment method of a head mounted display, the head mounted display including (a) an eyeglass type frame worn on the head of a viewer, and (b) two image display devices for the right and left eyes attached to the frame, and each of the image display devices including (A) an image forming device, and (B) an optical device adapted to receive, guide and emit light emitted from the image forming device, wherein the optical position adjustment method includes the step of: controlling an image signal that is supplied to the image forming device making up at least one of the image display devices so as to control the position of the image displayed on the optical device making up at least one of the image display devices and adjust the mutual positions of the two images.