The data storage array apparatus having a RAID configuration according to the present invention comprises an internal access issuance part 10 which issues internal access requests to data storage parts 6, a group response monitoring part 11 which monitors processing responses in the data storage parts 6 until an internal access requesting group satisfies a predetermined condition and issues a notice of completion of monitoring, an external access response part 12 which notifies to outside of completion of external access in response to a predetermined situation, a continuous response monitoring part 13 which further continuously monitors, based on the notice of completion of monitoring, processing responses for each HDD with respect to an internal access request which was met with no processing response from the data storage parts, and an array operation control part 14 which controls, based on continuous response monitoring information from the continuous response monitoring part, issuance of internal accesses to the respective data storage parts.