1. A voice conversation support apparatus for supporting a user to have a conversation, comprising: an input unit configured to accept a text data input according to a voice input mode and another input mode, wherein the voice input mode converts a voice uttered by the user into text data, wherein another input mode accepts an input operation from the user; a first determination unit configured to extract at least one subject keyword representing a current subject from the text data input; a second determination unit configured to extract a question pair of a question sentence and an answer sentence by determining whether the text data input is at least one of a question sentence and an answer sentence, and estimate a category of a word that can be an answer based on a format of the question sentence and the subject keyword, as a temporary answer category, when the text data input is the question sentence; a third determination unit configured to estimate a category of a answered content based on the answer sentence, and calculate a question pair likelihood based on at least one of the temporary answer category and the answer category, when the question pair is obtained; a scoring unit configured to calculate a score about a priority of each input mode based on the temporary answer category and the question pair likelihood; and a screen generation unit configured to display the input modes in an order of the scores calculated by the scoring unit.