1. A scroll display control device including a non--transitory computer readable medium which stores a program for causing a computer to execute scroll-displaying, in synchronism with reproduction of series information correlated to text information, the corresponding text information on a text display screen, said scroll display control device comprising: means which changes a scroll speed of a target text in said text display screen on the basis of a text quantity of said corresponding text information with respect to reproduction time of said series information, wherein a display area of the target text is fixed at a display reference position of the text display screen, a scroll speed calculation means which calculates said scroll speed of the target text on the basis of a time length of a series information section being reproduced, a quantity of the target text belonging to a target text section corresponding to said series information section, and text display setting information; a user instruction input means for dynamically changing the text display setting information related to the display reference position of the text display screen and the scroll method comprising a method for starting a scroll after a lapse of a predetermined time from a starting time of the target text, wherein text of a preceding text section which preceded the target text section and text of a succeeding text section which succeeds the target text section are respectively displayed in two adjacent areas across the target text section displayed at the display reference position of the text display screen, wherein the scroll speed calculation means calculates said scroll speed of the target text on the basis of the display reference position changed by the user instruction input means.
4. The scroll display control device according to claim 1 , wherein the series information is image information or sound information.