In a copy operation for a first sheet of requested plural sheets, a reading unit reads a document and a data conversion section converts the document image data into recording data. A recording unit records the recording data, while the recording data is stored in an image memory. A data amount of recording data to be stored in the image memory is determined. If, when a copy operation for a first sheet is completed, all of recording data is incapable of being stored in the image memory and the determined data amount of recording data is equal to or smaller than an available storage capacity of the image memory on condition that a read operation and a record operation are separately executed, a residual sheet record operation is executed by separately executing the read operation and the record operation.