A projection-type display device includes a liquid crystal device, a transmittance measuring device configured to measure a transmittance of a liquid crystal panel, and a cooling device. After a result of measurement of the transmittance by the transmittance measuring device changes by 10% relative to a default value, a control unit controls the cooling device to raise temperatures of a liquid crystal layer to be not less than 60° C. and not more than a nematic-isotropic phase transition temperature Tni-20° C. This makes it possible to efficiently sweep impurities from a display region to the outside of the display region without heating the liquid crystal layer more than necessary. In addition, a liquid crystal volume ratio V1/V2 of a liquid crystal device for blue among a plurality of liquid crystal devices is greater than that of the other liquid crystal panels, where V1 is a volume of liquid crystal at the inner side of a seal material, and V2 is a volume of the liquid crystal layer in the display region.