According to one embodiment, a storage controller includes a condition storage, a determination module, a wear-leveling block retainer, and a data transfer controller. The condition storage is provided in a storage including a plurality of blocks, and stores block condition information including at least one of erasure time information indicating when data is erased last time and erasure count information indicating the number of times data is erased. The determination module determines whether there is a block that requires wear leveling based on the block condition information. The wear-leveling block retainer retains block identification information that identifies a block determined to require wear leveling. The data transfer controller performs compaction to transfer data stored in blocks of the storage for collecting the data in a block, and, when the block identification information is retained, transfers data stored in the block identified by the block identification information.