A photosensor device, comprising: a body frame disposed in a bezel around an image display panel; a photosensor used to measure luminance and/or chromaticity of the image display panel; a sensor unit for causing the photosensor to receive light; a guide member configured to guide the sensor unit provided in the body frame, the guide member being provided adjacent to the sensor unit; a slide member configured to be slidable along the guide member, the slide member being provided on side adjacent to the body frame of the sensor unit, wherein the guide member has a first slope, and the slide member has a second slope, wherein the slide member is configured to slide along the guide member with the first slope and second slope facing each other;and drive means (551, 561) configured to move the sensor unit, wherein the photosensor and the sensor unit are disposed in the bezel, and wherein, by the drive means (551, 561), the sensor unit is configured to move to a measurement region on a display screen of the image display panel by performing a first rotation operation until the sensor unit is guided by the guide member, and wherein after the sensor unit is guided by the guide member, as the sensor unit slides on the guide member, the sensor unit is configured to approach the display screen by performing a second rotation operation in a direction perpendicular to a direction of the first rotation operation; and wherein the sensor unit and the drive means (551, 561) are coupled through a shaft, the shaft being disposed parallel to the body frame, wherein, by the drive means (551, 561), the shaft is configured to perform the first rotation operation in parallel with a display screen of the image display panel and on a plane parallel to the body frame, and as the sensor unit slides on the guide member, the sensor unit is configured to perform the second rotation operation around the shaft perpendicularly to the display screen. a body frame disposed in a bezel around an image display panel; a photosensor used to measure luminance and/or chromaticity of the image display panel; a sensor unit for causing the photosensor to receive light; a guide member configured to guide the sensor unit provided in the body frame, the guide member being provided adjacent to the sensor unit; a slide member configured to be slidable along the guide member, the slide member being provided on side adjacent to the body frame of the sensor unit, wherein the guide member has a first slope, and the slide member has a second slope, wherein the slide member is configured to slide along the guide member with the first slope and second slope facing each other;and drive means (551, 561) configured to move the sensor unit, wherein the photosensor and the sensor unit are disposed in the bezel, and wherein, by the drive means (551, 561), the sensor unit is configured to move to a measurement region on a display screen of the image display panel by performing a first rotation operation until the sensor unit is guided by the guide member, and wherein after the sensor unit is guided by the guide member, as the sensor unit slides on the guide member, the sensor unit is configured to approach the display screen by performing a second rotation operation in a direction perpendicular to a direction of the first rotation operation; and wherein the sensor unit and the drive means (551, 561) are coupled through a shaft, the shaft being disposed parallel to the body frame, wherein, by the drive means (551, 561), the shaft is configured to perform the first rotation operation in parallel with a display screen of the image display panel and on a plane parallel to the body frame, and as the sensor unit slides on the guide member, the sensor unit is configured to perform the second rotation operation around the shaft perpendicularly to the display screen.