An image display system comprising: an image display device; a first attachment; and a second attachment, wherein the image display device comprises: a frame wearable on a face of a user; a display unit (30R, 30L) configured to be arranged at least one of a position facing a right eye of the user and a position facing a left eye of the user in a case where the frame is worn on the face of the user; a display controlling unit configured to cause the display unit (30R, 30L) to display an image; and a joint portion (74R, 74L) provided on the frame, configured to have the first attachment mounted thereon, configured to have the second attachment mounted thereon, and configured to selectively have one of the first attachment and the second attachment mounted thereon when the image display device is used, the first attachment comprising an engaging portion (110, 120R, 120L, 130R, 130L) configured to engage with a head of the user and a first attaching portion (140R, 140L) configured to attach the engaging portion (110, 120R, 120L, 130R, 130L) to the joint portion (74R, 74L), the second attachment comprising a fixing portion (210R, 210L) configured to be fixed to an object configured to cover the user's head and a second attaching portion (220R, 220L) configured to attach the fixing portion (210R, 210L) to the joint portion (74R, 74L), and the joint portion (74R, 74L) comprising a first adjustment mechanism configured to relatively change mounting positions of the first attachment and the second attachment with respect to the frame. an image display device; a first attachment; and a second attachment, wherein the image display device comprises: a frame wearable on a face of a user; a display unit (30R, 30L) configured to be arranged at least one of a position facing a right eye of the user and a position facing a left eye of the user in a case where the frame is worn on the face of the user; a display controlling unit configured to cause the display unit (30R, 30L) to display an image; and a joint portion (74R, 74L) provided on the frame, configured to have the first attachment mounted thereon, configured to have the second attachment mounted thereon, and configured to selectively have one of the first attachment and the second attachment mounted thereon when the image display device is used, the first attachment comprising an engaging portion (110, 120R, 120L, 130R, 130L) configured to engage with a head of the user and a first attaching portion (140R, 140L) configured to attach the engaging portion (110, 120R, 120L, 130R, 130L) to the joint portion (74R, 74L), the second attachment comprising a fixing portion (210R, 210L) configured to be fixed to an object configured to cover the user's head and a second attaching portion (220R, 220L) configured to attach the fixing portion (210R, 210L) to the joint portion (74R, 74L), and the joint portion (74R, 74L) comprising a first adjustment mechanism configured to relatively change mounting positions of the first attachment and the second attachment with respect to the frame. a frame wearable on a face of a user; a display unit (30R, 30L) configured to be arranged at least one of a position facing a right eye of the user and a position facing a left eye of the user in a case where the frame is worn on the face of the user; a display controlling unit configured to cause the display unit (30R, 30L) to display an image; and a joint portion (74R, 74L) provided on the frame, configured to have the first attachment mounted thereon, configured to have the second attachment mounted thereon, and configured to selectively have one of the first attachment and the second attachment mounted thereon when the image display device is used, the first attachment comprising an engaging portion (110, 120R, 120L, 130R, 130L) configured to engage with a head of the user and a first attaching portion (140R, 140L) configured to attach the engaging portion (110, 120R, 120L, 130R, 130L) to the joint portion (74R, 74L), the second attachment comprising a fixing portion (210R, 210L) configured to be fixed to an object configured to cover the user's head and a second attaching portion (220R, 220L) configured to attach the fixing portion (210R, 210L) to the joint portion (74R, 74L), and the joint portion (74R, 74L) comprising a first adjustment mechanism configured to relatively change mounting positions of the first attachment and the second attachment with respect to the frame.