A projector device, comprising: an image generation unit (22, 25, 103a) that generates an image; an irradiation unit that irradiates light for projecting the image generated by the image generation unit (22, 25, 103a) upon a projection surface; a change unit (24, 103a) that changes luminance of the light irradiated from the irradiation unit; and a temperature information determination unit that determines temperature information in a neighborhood of the irradiation unit, characterised in that: the temperature information determination unit comprises a history storage unit that stores a history of light irradiation from the irradiation unit, an estimating unit that obtains a light emission time and a light non-emission time of the irradiation unit from the history of light irradiation from the irradiation unit and estimates a temperature in the neighbourhood of the irradiation unit based upon the light emission time and the light non-emission time of the irradiation unit obtained from the history of light irradiation from the irradiation unit, and a comparison unit that decides upon the temperature information by comparing the temperature estimated by the estimating unit with a predetermined value; and the change unit (24, 103a) changes the luminance of the light irradiated from the irradiation unit, based upon the temperature information determined by the temperature information determination unit. an image generation unit (22, 25, 103a) that generates an image; an irradiation unit that irradiates light for projecting the image generated by the image generation unit (22, 25, 103a) upon a projection surface; a change unit (24, 103a) that changes luminance of the light irradiated from the irradiation unit; and a temperature information determination unit that determines temperature information in a neighborhood of the irradiation unit, characterised in that: the temperature information determination unit comprises a history storage unit that stores a history of light irradiation from the irradiation unit, an estimating unit that obtains a light emission time and a light non-emission time of the irradiation unit from the history of light irradiation from the irradiation unit and estimates a temperature in the neighbourhood of the irradiation unit based upon the light emission time and the light non-emission time of the irradiation unit obtained from the history of light irradiation from the irradiation unit, and a comparison unit that decides upon the temperature information by comparing the temperature estimated by the estimating unit with a predetermined value; and the change unit (24, 103a) changes the luminance of the light irradiated from the irradiation unit, based upon the temperature information determined by the temperature information determination unit. the temperature information determination unit comprises a history storage unit that stores a history of light irradiation from the irradiation unit, an estimating unit that obtains a light emission time and a light non-emission time of the irradiation unit from the history of light irradiation from the irradiation unit and estimates a temperature in the neighbourhood of the irradiation unit based upon the light emission time and the light non-emission time of the irradiation unit obtained from the history of light irradiation from the irradiation unit, and a comparison unit that decides upon the temperature information by comparing the temperature estimated by the estimating unit with a predetermined value; and the change unit (24, 103a) changes the luminance of the light irradiated from the irradiation unit, based upon the temperature information determined by the temperature information determination unit.