A notification device for a mobile unit according to an embodiment includes, for example: a storage unit that stores therein first sound data; a sound output control unit that outputs a notification sound based on the first sound data, from a sound output unit provided on the mobile unit; a generation unit that generates second sound data by performing predetermined processing on a location of sound falling, while causing the first sound data to follow a cycle of the notification sound, the predetermined processing being different from processing on a location of sound rising; and a light source drive control unit that causes a light source unit provided on the mobile unit to emit light in accordance with the intensity of a sound expressed by the second sound data.