A data generating apparatus comprising: a converter configured to acquire conversion information in which a conversion rule is defined for converting first data, which is acquired by performing a maintenance operation using a device maintenance apparatus for devices configuring a distributed control system that is built in a plant, into second data processable by a facility maintenance management system and to convert the first data in accordance with the conversion rule defined in the acquired conversion information to generate the second data; a storage storing a plurality of pieces of conversion information prepared for a plurality of facility maintenance management systems; a selector configured to select one piece of conversion information from among the plurality of pieces of conversion information; and an output (23, 33) configured to output the second data generated by the converter, wherein the converter is configured to acquire from the storage the one piece of conversion information selected by the selector, wherein the converter is configured to perform a first process of integrating or combining the first data in accordance with the conversion rule defined in the conversion information, wherein the first data comprises first original data and second original data, types of the first original data and second original data being different from each other, wherein the first original data comprises a tag, a date, and a first element, wherein the second original data comprises a tag, a date, and a second element, and wherein the converter is configured to perform the first process of combining records in which the tag of the first original data and the tag of the second original data coincide with each other and the date of the first original data and the date of the second original data coincide with each other to generate combination data which comprises the tag, the date, the first element, and the second element. a converter configured to acquire conversion information in which a conversion rule is defined for converting first data, which is acquired by performing a maintenance operation using a device maintenance apparatus for devices configuring a distributed control system that is built in a plant, into second data processable by a facility maintenance management system and to convert the first data in accordance with the conversion rule defined in the acquired conversion information to generate the second data; a storage storing a plurality of pieces of conversion information prepared for a plurality of facility maintenance management systems; a selector configured to select one piece of conversion information from among the plurality of pieces of conversion information; and an output (23, 33) configured to output the second data generated by the converter, wherein the converter is configured to acquire from the storage the one piece of conversion information selected by the selector, wherein the converter is configured to perform a first process of integrating or combining the first data in accordance with the conversion rule defined in the conversion information, wherein the first data comprises first original data and second original data, types of the first original data and second original data being different from each other, wherein the first original data comprises a tag, a date, and a first element, wherein the second original data comprises a tag, a date, and a second element, and wherein the converter is configured to perform the first process of combining records in which the tag of the first original data and the tag of the second original data coincide with each other and the date of the first original data and the date of the second original data coincide with each other to generate combination data which comprises the tag, the date, the first element, and the second element.