(57) An update processing system for an automated teller machine connected to a host computer, including: a holding memory for storing accumulated data consisting of reference data and transaction data; a holding date management unit operatively connected to the holding memory, and for reading the accumulated data from the holding memory, updating the reference data based on the data already updated by the host computer, and writing the transaction data to the holding memory; a pending transaction unit operatively connected to the holding data management unit and the host computer, and for controlling the update processing of the holding data management unit based on the reception request from the host computer, and sending the transaction data read out by the holding data management unit to the host computer based on the transmission request from the host computer; and a transaction unit operatively connected to the holding data management unit, and for requesting a read or write of the accumulated data from or to the holding data management unit.