A distance measuring device according to an embodiment includes a time acquisition circuit and a distance measurement circuit. The time acquisition circuit acquires a rising time in which a measurement signal obtained by converting reflected light of a laser beam from an object into a signal reaches a first threshold and a falling time in which the measurement signal reaches a second threshold after reaching the first threshold. The distance measurement circuit measures the distance to a target object on the basis of a time difference between timing based on the rising time and the falling time and irradiation timing of the laser beam.