PURPOSE: To arbitrarily select the resolution, without the change of a code table for RL encoding, the transmitting picture information to be encoded through encoding after the multiplication of a prescribed constant to the run length of the information.

CONSTITUTION: If a changing point is detected to picture information 21 read from an original by a reader 10, an RL value 31 is outputted from an RL counter 12 and inputted to a shift register 18. The shift register 18 shifts the RL value by one bit, inputs an RL' value 35 to an ROM14, and the ROM14 writes this encoded data 33 to the upper-order of the LSB of a shift register 16 adjacently. A controller 13 reads out all the data preset in a counter 15 and the shift register 16 as an encoded data 30 and obtains a data 40 encoding the RL' value by storing the data 30 to an FIFO buffer 17. In this case, since the RL' value is a half the RL value, the double resolution can be obtained at a a decoder.