A display device comprising: first, second and third display elements; a first light source configured to emit a first illumination light having a first wavelength band of visible light; a second light source configured to emit a second illumination light having a second wavelength band of infrared light; a signal synthesizing unit configured to receive a first image input signal (S v) and a second image input signal (S I) and to generate a mixed image signal (S F) in which first frames of the first image input signal (S v), which is meant for displaying an image based on the first illumination light, and second frames of the second image input signal (S I), which is meant for displaying an image based on the second illumination light, are repeated in an alternate manner; a pixel control unit configured to, based on the mixed image signal (S F), control a voltage applied to the display elements; and a light source control unit configured to control the first light source to emit the first illumination light in the first frames and to turn off the first illumination light in the second frames, and further configured to control the second light source to emit infrared light in the second frames and to turn off the second illumination light in the first frames, wherein the display device is configured to obtain a blue visible light, a red visible light and a green visible light from the first illumination light emitted by the first light source in the first frames, and to direct the red visible light onto the first display element, the green visible light onto the second display element, and the blue visible light onto the third display element, and is further configured to direct the second illumination light emitted from the second light source in the second frames only onto the first display element from among the first display element, the second display element and the third display element, wherein the pixel control unit is configured: in the first frames: to control a voltage applied to each of the first to third display elements according to a respective signal value of the first image input signal (S v), and, in the second frames: to control a voltage applied to the first display element according to a signal value of the second image input signal (S I) and at same time, regardless of signal value of the second image input signal (S I), set a voltage applied to the second and third display elements to a constant value. first, second and third display elements; a first light source configured to emit a first illumination light having a first wavelength band of visible light; a second light source configured to emit a second illumination light having a second wavelength band of infrared light; a signal synthesizing unit configured to receive a first image input signal (S v) and a second image input signal (S I) and to generate a mixed image signal (S F) in which first frames of the first image input signal (S v), which is meant for displaying an image based on the first illumination light, and second frames of the second image input signal (S I), which is meant for displaying an image based on the second illumination light, are repeated in an alternate manner; a pixel control unit configured to, based on the mixed image signal (S F), control a voltage applied to the display elements; and a light source control unit configured to control the first light source to emit the first illumination light in the first frames and to turn off the first illumination light in the second frames, and further configured to control the second light source to emit infrared light in the second frames and to turn off the second illumination light in the first frames, wherein the display device is configured to obtain a blue visible light, a red visible light and a green visible light from the first illumination light emitted by the first light source in the first frames, and to direct the red visible light onto the first display element, the green visible light onto the second display element, and the blue visible light onto the third display element, and is further configured to direct the second illumination light emitted from the second light source in the second frames only onto the first display element from among the first display element, the second display element and the third display element, wherein the pixel control unit is configured: in the first frames: to control a voltage applied to each of the first to third display elements according to a respective signal value of the first image input signal (S v), and, in the second frames: to control a voltage applied to the first display element according to a signal value of the second image input signal (S I) and at same time, regardless of signal value of the second image input signal (S I), set a voltage applied to the second and third display elements to a constant value. in the first frames: to control a voltage applied to each of the first to third display elements according to a respective signal value of the first image input signal (S v), and, in the second frames: to control a voltage applied to the first display element according to a signal value of the second image input signal (S I) and at same time, regardless of signal value of the second image input signal (S I), set a voltage applied to the second and third display elements to a constant value.