To reduce weight and size by simplifying a structure and to reduce a manufacturing cost.

In this cathode-ray tube light source device, a fluorescent substance formation part is formed in a light emission part 3 of a cathode-ray tube device. The light emission part 3 is a single light emission area or is formed by arranging a plurality of light emission areas in a single axis direction. The plurality of light emission areas are selected from, for instance, white, red, green and blue phosphors. The cathode-ray tube light source device is so structured as to satisfy an expression of Scrt*{sinθcrt(1/2)}2=Svalb*{sinθvalb(1/2)}2 and an expression of Scrt<Svalb among an area Scrt and a light capture angle θcrt of the light emission part 3, and a light entering area Svalb and a light capture angle θvalb of a spatial modulation element (light bulb 12). A transmission/reflection type MEMS or an LCD can be used for the spatial modulation element.