1. A speech translation system comprising: a first terminal device comprising a first speech input for inputting a first speech of a first language spoken by a first user, and converting the first speech to a first speech signal; a second terminal device comprising a second speech input for inputting a second speech of a second language spoken by a second user, and converting the second speech to a second speech signal; a speech recognition device that receives the first speech signal and the second speech signal, recognizes the first speech signal to a first recognized text, and recognizes the second speech signal to a second recognized text; a machine translation device that receives the first recognized text and the second recognized text, translates the first recognized text to a first translated text of the second language, and translates the second recognized text to a second translated text of the first language; and a control device; wherein the first terminal device receives (a) a first text set of the first language being the first recognized text and the second translated text, and (b) a second text set of the second language being the second recognized text and the first translated text, and comprises a first display unit that displays the first text set and the second text set; and the second terminal device receives at least one text of the second text set, and comprises a second display unit that displays the at least one text of the second text set.