A projection type projector, comprising: a light modulation part configured to modulate light generated by a light source part; a video signal processing part configured to process a video signal to be input; and a projection optical system projecting the light modulated by said light modulation part onto an external projection target to obtain a projected video image, wherein said video signal processing part is configured to include a blue light effect alleviating part (501 to 507) alleviating effects of blue light on retinas, characterized in that said blue light effect alleviating part is configured to determine whether among a red signal, a green signal, and a blue signal included in the video signal, a ratio of a sum of red signal and green signal to a sum of signals included in the video signal is smaller than a specified value, and in a case where the ratio of the sum of red signal and green signal to the sum of signals included in the video signal is smaller than the specified value, to generate a blue light effect alleviating signal for controlling said light source part to reduce the brightness of said projected video image as a whole. a light modulation part configured to modulate light generated by a light source part; a video signal processing part configured to process a video signal to be input; and a projection optical system projecting the light modulated by said light modulation part onto an external projection target to obtain a projected video image, wherein said video signal processing part is configured to include a blue light effect alleviating part (501 to 507) alleviating effects of blue light on retinas, characterized in that said blue light effect alleviating part is configured to determine whether among a red signal, a green signal, and a blue signal included in the video signal, a ratio of a sum of red signal and green signal to a sum of signals included in the video signal is smaller than a specified value, and in a case where the ratio of the sum of red signal and green signal to the sum of signals included in the video signal is smaller than the specified value, to generate a blue light effect alleviating signal for controlling said light source part to reduce the brightness of said projected video image as a whole. a video signal processing part configured to process a video signal to be input; and a projection optical system projecting the light modulated by said light modulation part onto an external projection target to obtain a projected video image, wherein said video signal processing part is configured to include a blue light effect alleviating part (501 to 507) alleviating effects of blue light on retinas, characterized in that said blue light effect alleviating part is configured to determine whether among a red signal, a green signal, and a blue signal included in the video signal, a ratio of a sum of red signal and green signal to a sum of signals included in the video signal is smaller than a specified value, and in a case where the ratio of the sum of red signal and green signal to the sum of signals included in the video signal is smaller than the specified value, to generate a blue light effect alleviating signal for controlling said light source part to reduce the brightness of said projected video image as a whole.