PURPOSE: To reduce the unevenness of transmission by selecting the driving speed of each divided block of subscanning in accordance with the number of encoded information, dividing also main scanning into plural blocks and synchronizing the driving of a subscanning block with the recording of a main scanning block.

CONSTITUTION: An encoded signal is demodulated by a modulator and demodulator (MODEM)1, sent to a buffer memory 2 to store it and decoded by a decoding circuit 3. A buffer memory stored bit detecting circuit 7 detects the number of bits stored in the buffer memory 2 at the completion of driving of the preceeding block and sends a buffer memory stored bit signal 9 representing the number of detected bits to a subscanning control circuit 8. The subscanning control circuit 8 selects the driving speed of the succeeding block, the same as the preceding block, slower by one step or faster by one step, on the basis of the compared result between the number of stored bits previously set up in the buffer memory 2 and the number of encoded bits stored in the buffer memory 2, and also synchronizes the driving pulse of each subscanning block with the recording timing of each main scanning block.