An image processing device adjusting pixel-luminance characteristics is provided; the image processing device is provided with an image acquiring unit that acquires the image from an imaging unit mounted on a vehicle, a light determining unit that determines a state of a light mounted on the vehicle, and an adjusting unit that adjusts a relationship between a luminance at an object to be capturedby the imaging unit, and a pixel value in the image. The adjusting unit is configured to set, when the light determining unit determines the state of the light is in the low-beam state, the illuminance where the pixel value is at the lower limit, to be lower than that of a case when the light determining unit determines the state of the light is in the high-beam state.