According to one embodiment, a data storage apparatus including memory chips includes an error correction encoder, a RAID controller, error detectors and memory units. Each of the memory chips includes a semiconductor memory. The error correction encoder adds an error correction code to an encoded data stream. The RAID controller divides the encoded data stream from the error correction encoder into data blocks. The RAID controller generates a parity data block based on the data blocks. The RAID controller outputs the data blocks and parity data block to the error detectors, respectively. The error detectors add an error detection code to the data blocks and parity data block output from the RAID controller. Each of the memory units includes the memory chips. The memory units write the data blocks and parity data block from the error detectors to the memory chips.