A medium supply device includes: a loading unit on which media are loadable in an up-down direction; a supply unit that supplies air to a plural media loaded on the loading unit to float and separate the plural media; a transporting unit that sequentially feed the media that are floated and separated by the supply unit; a photographing unit that photographs a state in which the media are floated and separated by the supply unit; and a light irradiation unit that irradiates end portions of the media on a photographing side of the photographing unit with light from a plural different positions in the up-down direction.