To provide a semiconductor device to which information can be input in low-illuminance conditions or at a location distant from the semiconductor device. An ultrasonic wave sensor is provided in the semiconductor device with a display region having photosensors. An object to be detected is detected by switching the photosensors and the ultrasonic wave sensor in accordance with illuminance around the semiconductor device or a distance between the semiconductor device and the object. The photosensors and the ultrasonic wave sensor can be used concurrently.