Device and method for compensating a picture quality of a projection type display, the device including a screen for displaying a picture projected from outside of the screen, a video processing part for receiving, and converting an analog video signal into a digital video signal, and adjusting an offset and a gain thereof, for making the video signal displayable on the screen, a sensing part for sensing the video signal from the video processing part and projected to a region of the screen, a memory part for storing reference video information, and a microcomputer for projecting the reference video information stored at the memory part onto the screen through the video processing part according to a user's picture quality compensation command, or a preset algorithm, and controlling the video processing part so that a luminance and chromaticity of the picture are calculated according to an output of the sensing part, the luminance and the chromaticity of picture are compared to preset values, and a compensation is made according to a result of the comparison, thereby automatically compensating a picture quality deterioration to an optimal condition to prevent a picture quality deterioration regardless of factors that affect the picture quality.