PURPOSE: To carry out an efficient split recording by use of a small number of switching circuits by masking an input recording signal to render it into a signal containing no record before or after the input signal containing a record among the recording signals reaches a predetermined value.

CONSTITUTION: In a period where a stroke signal 101 is emitted, a recording signal 102 and a transfer clock pulse 103 are sent to a dot counter 14, and only when the signal 102 shows a signal containing a record (hereunder referred to as black) pulses 103 are counted. A dot counter 20 generates a carry pulse 110 when a number of black reaches a predetermined value, and a counting of an upper order counter 15 is carried by one. A data converter 16 generates a coincident signal between the output of the counter 15 and an output of a counter 17. During this period of time, a gate 18 is opened, and the signal 102 is sent as a recording signal 108 to a data register, whereby the recording data including a predetermined value of black is memorized in the data register by the pulse 103.