Video image compression/decompression device

An image compression/decompression device achieving increased utilization efficiency of the memory bandwidth in the access to the memory used for the compression/decompression operation while maintaining ill effect on the images at a low level is realized. The image compression/decompression device comprises a data conversion unit which reduces the data access rate when original images (as input images at the time of performing the compression) and reference images (used for performing the interframe prediction) are stored in the memory by accessing the memory. The access to the memory is performed in an address sequence (order) that differs between data write and data read. This makes it possible to increase the utilization efficiency of the memory bandwidth, and further to reduce the capacity of the buffer memory used for the data read.