A bias light supply device applies bias light through a color separation stripe filter to a color TV imaging device which generates a multiplex color TV video signal. The bias light supply device is disposed in front of the color TV imaging device and is made up of a bias light source for emitting bias light, and a light conducting member made of acrylic resin or glass to apply bias light from the bias light source to the imaging device through the filter. Arranged parallel to the surface of a photoelectric transducer section, the light conducting member has light inlet portions, reflective portions and light outlet portions and is mounted in an opening formed in a color TV camera casing. All the outer surfaces of the light conducting member, except for the light inlet portions, reflective portions and light outlet portions, are covered with light intercepting members. The quantity and color temperature of the bias light are adjustable. The bias light supply device may reduce afterimages and improve color reproducibility in dark scenes.