PURPOSE: To impose efficient speed modulation by the velocity modulation (VM) device of the three-tube type projection television in consideration of the specific sensitivity characteristics of the eye to the primary colors R, G, and B.

CONSTITUTION: The velocity modulation device of the three-tube type projection television has a VM signal extracting circuit 1 which extracts a velocity modulation signal from a brightness signal, driving circuits 3-5 whose gain ratios are 0.3, 0.59, and 0.11, and a VM coil 7 for red, a VM coil 8 for green, and a VM coil 9 for blue which are driven by those driving circuits 3-5 and arranged for corresponding cathode-ray tubes. The gains of the driving circuits 3-5 are set corresponding to the specific sensitivity of the eye corresponding to the primary colors R, G, and B, so the speed modulation conforming with actual contour emphasis is imposed. Consequently, a waste of electric power is eliminated.