Interleave control device, interleave control method, and memory system

According to one embodiment, an interleave control device of a memory system includes a memory divided into sections, and a data bus used, in common, for data transfers for the sections, the device comprises a detector and a start module. The detector is configured to detect a transfer of data of a predetermined size during a transfer of data on the data bus to be written to a certain section of the memory or data read from the section. The start module is configured to start a transfer of interleave control data in place of the data to be written or the read data when the detector detects the transfer of the data of the predetermined size.