To provide a retrieval device capable of retrieving in consideration of the diversity of input content expression.SOLUTION: An information retrieval device 100 comprises: a question input section 101 that receives a retrieval query from a user; a distribution estimation section 102 that estimates a Gaussian distribution in a semantic space of the retrieval query; a first memory section 103 that stores information (average μ and covariance s) for identifying the Gaussian distribution in each semantic space for retrieval data, which is a plurality of pieces of predetermined text data; a distribution retrieval section 104 that retrieves text data having high similarity to the retrieval query on the basis of the information (average μ and covariance s) for identifying the distribution of the text data stored in the first memory section 103 in the semantic space and the Gaussian distribution estimated by the distribution estimation section 102; and an output section 105 that outputs the text data retrieved by the distribution retrieval section 104.SELECTED DRAWING: Figure 1