An image processor includes: an image sensor outputting a short exposure image and a long exposure image; a sensor controller that, when brightness of the subject changes, controls first exposure sensitivity to cause the short exposure image to have first brightness and controls second exposure sensitivity to cause the long exposure image to have second brightness; a motion blending ratio calculator calculating a motion blending ratio based on a motion amount of the subject; a motion-adapted image synthesizer generating a motion-adapted image by synthesizing a corrected short exposure image and the long exposure image based on the motion blending ratio; and an HDR image synthesizer generating an HDR image by synthesizing the motion-adapted image and the short exposure image together. When the subject becomes darker, the sensor controller controls the first and second exposure sensitivities to cause the first sensor gain to be at most the second sensor gain.