To solve the problem that a DMA means is also used for other treatment than processing of data, to increase a DMA bus share and to take time for a DMA transfer process in an ink jet recorder which uses the DMA means also to read also recording data of a printing buffer having a flag (null flag) set thereto, and converts the read data to null data (zero data) at all times because the recording data of the printing buffer has the flag set without being stored in the printing buffer in the case where the data is zero in a predetermined direction.

In the case where all null flags are set at a scanning time, a process of reading out by the DMA means from the printing buffer is interrupted, thereby restricting a DMA transfer frequency.