A cash transaction machine performs receiving and/or paying transactions of bills by manipulation of a user, transfers bills between a receptacle (1) where bills are paid in and out and a storage (8, 9) where bills are stored, and by using a sterilizing unit (11) for heat-sterilizing bills being transferred, detects the temperature of the sterilizing unit with a temperature detector (20), controls the temperature of the sterilizing unit so as to be in a specified temperature range, and also controls the processing of transactions by, for example, temporarily stopping the transaction according to the detected temperature.