Provided are a content transfer system, a content transfer method, and a home server capable of backing up all backup target contents without having to transfer all backup target contents. This content transfer system includes a home storage and an online storage. The home storage transfers identifying information of a backup target content to the online storage and requests the online storage to determine the existence of a content that is identical to the backup target content upon requesting the online storage to back up the backup target content, transfers metadata to the online storage when an identical content exists in the online storage, and transfers the backup target content to the online storage in all other cases.