PURPOSE: To obtain a two-dimension compressor able to improve the compressing efficiency for a signal by changing a block size in response to an error rate of a transmission line or a recording medium so as to suppress generation of error.

CONSTITUTION: Picture information of an original stored in a picture memory 11 is fed to a compression processing section 13 in response to the control of a transmission control section 12 and is subject to compression processing (coding) at the section 13 in response to the block size from a block size generating section 14. The block size generation section 14 is to obtain a block size K proper to the error rate R specified in advance according to the characteristic of a transmission line 15. Then the compressed signal is fed to an stretch processing section 16 at the reception side via the transmission line 15 and reproduced at the section 16 and the result is fed to a picture memory 17. The expanding processing section 16 counts the bit number in one line, the count value is compared with a reference value at an error detecting section 18 and when the result is different, an error signal is generated.