Abstract: A printer which comprises a buffer memory for temporarily storing therein new print data, a full dot memory for holding therein a dot-developed print data in a dot pattern on a page basis, a buffer memory management table for managing the state of the print data of the buffer memory on the page basis, and a control means. The control means, when it is desired to store the new print data in the buffer memory, judges whether or not a page of the new print data is the same as a page of print data whose printing is not completed or being discharged. When the control means determines that the page of the new print data is the same as that of the print data being discharged, the control means stores the new print data in the buffer memory immediately after the dot development of the print data of the buffer memory on the full dot memory is completed.