A projection-type display apparatus for projecting an image onto a screen includes a light source, a signal processing unit for processing an input image signal to output a first image signal representing first primary-color information R1, G1, and B1 representing values of red, green, and blue components of an image to be projected, a signal conversion unit for converting the first image signal into a second image signal representing a coefficient M which depends on luminance of the image to be projected defined by the first primary-color information R1, G1, and B1, and into a third image signal representing second primary-color information R2=R1/M, G2=G1/M, and B2=B1/M. The projection-type display apparatus also includes a first light valve for modulating light received from the light source in accordance with the coefficient M, the light changing in color among red, green, and blue, a second light valve for further modulating the light received from the first light valve in accordance with the second primary-color information R2, G2, and B2 in sequence, and a projection unit for throwing the light received from the second light valve onto the screen.