Disclosed is a connector cover structure of a bill storage box, which can prevent a connector for electric power supply from being exposed to dust or foreign substances, during the process of mounting or dismounting a cassette box in or from the bill storage box. The disclosed connector cover structure includes: a connector-fixing bracket fixedly assembled with the connector, and having assembling holes formed through opposite sides of the connector-fixing bracket; a cover having a hinge shaft rotatably fitted in the assembling holes of the connector-fixing bracket, thereby covering a connecting pin; a contact part protruded by a certain length in front of one end of the cover, and having a curved shape; and elastic springs fixedly assembled to the hinge shaft in such a manner that the cover can be returned to its original position. Accordingly, it is possible to prevent poor connection or electrical short circuiting by preventing the exposure of the connector to dust or foreign substances.