The word string extraction unit 40 analyzes the text data to be analyzed, and extracts a word string whose appearance frequency in the text data to be analyzed satisfies a predetermined condition among word strings detected in the text data to be analyzed.

First, the text data to be analyzed is inputted to the word string extraction unit 40. The text data to be analyzed may be, for example, text data provided by a server on the Internet. Text data acquired from one or more servers may be inputted to the word string extraction unit as data to be analyzed.

The type of the server is not limited. For example, a social media server may be used. In this case, text data that has been uploaded by multiple users and is not restricted to be disclosed is inputted to the word string extraction unit 40 as text data to be analyzed.

In addition, the server may be an information providing server that provides the latest news and the like. In this case, text data, such as news published as a web page, is input to the word string extraction unit 40 as text data to be analyzed.

For example, data over several hours, several days, several weeks, several months, and several years may be inputted to the word string extraction unit 40 as data to be analyzed.

The text data to be analyzed does not need to be data on the Internet. For example, text data created by the user and stored locally may be inputted to the word string extraction unit 40 as data to be analyzed.

In a case where the text data to be analyzed is inputted, the word string extraction unit 40 analyzes the text data and detects multiple word strings in the text data to be analyzed.