To effectively reduce the load on a device involved in converting the format of content data. A storage unit (14) stores format information that includes at least information about the container format of first content data and encoding information about multimedia data included in the first content data; and a container converter (16) converts the second container format of second content data into the first container format of the first content data on the basis of information stored in the storage unit (14), without decoding the multimedia data included in the second content data and without encoding the multimedia data obtained as a result of the decoding, whereby the first content data is generated.