A projection-type image display apparatus includes a display device and a projection optical system. The the carrier device includes a strap member being designed for being selectively coupled to the walker. The method also includes determining a relationship between an FMEA indicator of the FMEA generated for the at least one product and the historical data for the at least one product. The multiple protruding portions come in contact with an inserted portion inner peripheral wall surface of the end cap inserted portion.