Natural language processing is one of the major research fields in artificial intelligence (AI), and is a technology for processing the language we use in our daily life (natural language) by computers. In our laboratory, we conduct research on so-called text mining, which is a technique for finding valuable information from large amounts of text data using natural language processing. Particularly, we develop text mining techniques for technical documents such as patents, research papers, and SNS data, and some of our research products are used in several companies and research institutes.