A stereo camera adjustment system disposes an adjustment plate that displays an adjustment chart for adjusting deviation of image information caused by position misalignment of the stereo camera at a predetermined position relative to a vehicle mounted with a stereo camera, capture an image of the adjustment chart, and process the captured image of the adjustment chart to correct the deviation of the image information. The stereo camera adjustment system includes a plate movement device that adjusts a disposed state of the adjustment plate relative to the vehicle, a detector that detects an attitude of the vehicle stopped at a defined position, and a controller that controls, based on the detected attitude of the vehicle, the plate movement device to adjust the disposed state of the adjustment plate such that the adjustment plate is at the predetermined position relative to the vehicle.