An information processing apparatus, backup method, and program product that enable efficient differential backup. In one embodiment, an information processing apparatus for files stored in a storage device includes: a metadata management unit for managing metadata of files stored in the storage device; a map generation unit for generating a map which indicates whether metadata associated with an identification value uniquely identifying a file in the storage device is present or absent; and a backup management unit for scanning the metadata to detect files that have been created, modified, or deleted since the last backup, and storing at least a data block and the metadata for a detected file in a backup storage device as backup information in association with the identification value.