Display system, program, display method, and head mounted device

A display method comprising:

• by a computer,
• displaying a moving image on a display surface;
• obtaining image information photographed by an imaging unit for photographing a front of the display surface;
• obtaining position information of an optical axis of an optical system on the display surface, the optical system being included in a head mounted device configured to be mounted on a head of a user, and the optical system guiding image light of the moving image to an eye of the user, on a basis of position information of at least two reference positions whose relative positions with respect to the optical axis are determined in advance, the at least two reference positions being included in the image information;
• and
• displaying the moving image in a region of the display surface according to the position information of the optical axis.

A head mounted device comprising:

• a mounting band configured to be mounted on a head of a user;
• a housing portion configured to house a portable terminal having an imaging unit for photographing a front side of a display surface displaying a moving image;
• an optical system configured to guide image light emitted from the display surface to an eye of the user;
• and
• at least one reflecting mirror configured to reflect the image light to the imaging unit.