An information processing apparatus (10) includes: a formal language query accepting unit (12) that accepts a query expression and correct answer data; a semi-structured data accepting unit (14) that accepts semi-structured data that includes text nodes; a node text extraction unit (16) that extracts natural language text from the text node, as node text; a node text expression generation unit (18) that receives the node text from the a converter (100) and obtains node text expressions; an answer calculation unit (20) that calculates an answer to the query expression with use of the node text expressions; and an update unit (22) that, if the answer calculated by the answer calculation unit (20) matches the correct answer data, updates parameters in the converter (100) such that the corresponding node text expression is more likely to be output in the converter (100).