With the psychological fact taken into account that a comfortable colour sensation cannot be produced under conditions of dim lighting with high colour temperatures, it can be deduced that the ideal source of lighting for a museum is a lamp whose energy distribution curve corresponds to that of a black body with a colour temperature capable of being comfortable in a subdued light. Of such light sources the fluorescent lamp seems most suitable for our purposes, because it gives off little heat when installed in a show case, which is our usual recourse in exhibiting our delicate art objects. The authors have conducted measurements on various fluorescent lamps on sale and presented their respective energy distribution curves so obtained. They leave the choice at the reader's disposal, with observations on the following three conditions: 1) With no ultra-violet rays, 2) With an energy distribution curve as similar as possible to that of a black body, and 3) With minimum effect of line spectra of mercury. Written in Japanese, with an English abstract. -- AATA