A data communication apparatus and an electronic mail data producing method are provided that are capable of allowing a file name to be easily added to a file attached to an electronic mail and also allowing a file name to be added to a file attached to an electronic mail, which is commensurate with the contents of the date to be transmitted. A CPU of the data communication apparatus combines a page number allotted to each of the images converted into files with the subject of the electronic mail that is inputted, to generate an attached image file name, and transmits the electronic mail with the image data in the form of files attached thereto together with the generated attached image file names. Therefore, it is not necessary to input the name of an image file attached to an electronic mail, which facilitates the operation of transmitting an electronic mail and enables giving a file name that enables the receiver of the electronic mail to easily recognize the contents of the attached image file.