To provide a picture processor capable of preventing the generation of noise on a screen to be compressed or enlarged.

An address comparator 18 in the picture processor 1 compares a raster address RAD for accessing a picture memory 5 in each raster unit with a block address BAD for accessing the memory 5 in each block unit. When the block address BAD exceeds the raster address RAD, the comparator 18 outputs an H level stand-by signal WS. A memory controller 13 stops access to the memory 5 in each block unit based upon the H level stand-by signal and a JPEG codic 15 stops compressing/enlarging operation.