A good fitting sensation of a lens unit is obtained by performing fine adjustment of the position and angle of the lens unit. A lens unit attachment mechanism includes a frame member supporting a pair of lenses, side frame members extending rearward of the lenses from left and right end portions of the frame member, an angle adjustment member coupled to the lens unit and having two rotation pivot points, and a position adjustment retention member retaining the angle adjustment member so as to allow extending and retracting. The lens unit attachment mechanism adjusts the position and angle of the lens unit flexibly.