1. A text mining device, comprising: a computer device that includes a processing device, a memory readable by the processing device, and a storage unit readable by that processing device, the memory having stored program code sufficient to cause the computer device, upon execution by the processing device, to operate as: a data input unit that receives, as input, audible speech and converts said speech to an input text set intended to be a target of text mining; a language processing unit that performs language processing for one or more portions of the input text set and outputs and stores a plurality of text elements; a topic involvement degree calculation unit that calculates and stores a topic relatedness degree that indicates a degree to which each text element relates to an analysis target topic received by the user and stored; and an element identification unit that, for each text element, calculates and stores a topic involvement degree on the analysis target topic with respect to the text element, calculates and stores an appearance degree by counting a number of times the text element appears in the input text set, said appearance degree indicating a degree to which the text element appears in each portion of the input text set corresponding to the analysis target topic, corrects the calculated appearance degree of the text element by multiplying the calculated appearance degree with the topic involvement degree to produce and store a corrected appearance degree, calculates and stores, using the corrected appearance degree, a feature degree as an index of a degree to which the text element appears within the input text set, and using the feature degree, identifies, stores and outputs, via an output unit, a distinctive text element within the input text set on the basis of the calculated feature degree, wherein the feature degree is a degree that a word of the input text set, a word n-Gram, a segment, or dependency thereof, or n consecutive dependency thereof, or each element divided into a unit of a partial tree of a syntax tree, or any combination of the foregoing appears within the input text set, where n is a natural number.