To enable a medium made up of a cut form such as a transfer form to be supplied to a document processor under a simple constitution.

This medium supply device comprises a feeder roller which feeds the medium made up of a specified document into the main body of the document processor, a loading stand which loads the medium, and is installed in a freely movable way that the stand can finds its way to the feeder roller side and can recede from the feeder roller side, an urging means which always urges the loading stand to the feeder roller side, a lever which makes the loading stand recede from the feeder roller side, resisting the urging means, and a drive mechanism which drives the lever.