An endoscope system is provided that includes a processor connectable to various endoscopes to process signals generated by the endoscope being connected. The processor further includes a database, a data selector and a data register. The database is configured to be registered a plurality of pieces of endoscope data, each of which being related to different one of the endoscopes connectable to the connector. Each piece of the endoscope data includes priority information indicating the priority of deleting the piece of endoscope data. The data selector selects one piece of the endoscope data based on the priority information. The data register registers a new endoscope with the database by replacing the selected piece of endoscope data with the piece of endoscope data of the new endoscope.