6. The captioned image reproducing device according to claim 1 , wherein: the caption text contains a received caption contained in broadcasting data transmitted from an external device and the dummy caption; the captioned image reproducing device further comprises a caption list display unit that displays the caption list and a switching unit that switches a mode between a first mode that the caption list includes therein only the received caption and a second mode that the caption list includes therein the received caption and the dummy caption; the control unit adds an identifier indicating that a caption text is the received caption or the dummy caption to a caption text stored in the memory unit; and when the switching unit switches the mode, the caption list creating unit determines the identifier added to the caption text, and creates a caption list based on a determination result.
6. The captioned image reproducing device according to claim 1 , wherein: the caption text contains a received caption contained in broadcasting data transmitted from an external device and the dummy caption; the captioned image reproducing device further comprises a caption list display unit that displays the caption list and a switching unit that switches a mode between a first mode that the caption list includes therein only the received caption and a second mode that the caption list includes therein the received caption and the dummy caption; the control unit adds an identifier indicating that a caption text is the received caption or the dummy caption to a caption text stored in the memory unit; and when the switching unit switches the mode, the caption list creating unit determines the identifier added to the caption text, and creates a caption list based on a determination result. 10. The captioned image reproducing device according to claim 6 , further comprising: an image creating unit that creates a picture image indicating the length of a total reproduction time of a content stored in the memory unit; an image synthesizing unit that synthesizes a predetermined first image with the picture image at a position corresponding to the reproduction start information of the caption text to which an identifier indicating that the caption text is the received caption is added, and synthesizes a predetermined second image with the picture image at a position corresponding to the reproduction start information of the caption text to which an identifier indicating that the caption text is the dummy caption is added; and a display unit that displays a synthesized image synthesized by the image synthesizing unit.