To mount easily a substandard lamp member desired for a lamp housing of a moving body.

This method is for mounting the substandard lamp member on the lamp housing of the moving body, and it has an elastic deformation function and an elastic restoring function of material quality itself in a locking hole formed in the lamp housing, at least at the base of the lamp protruding from a bulb socket, and furthermore a cylindrical fitting member of which the outside dimension is larger than the inner diameter of the locking hole is removably fitted outside, and the substandard lamp member in a state that the fitting member is picked up is fitted to the lamp housing.