1. An information processing apparatus comprising: a web page acquiring unit that acquires a plurality of web pages of an identical category into which targets stated in web pages are classified; an initial data acquiring unit that acquires as initial data an attribute-related term related to an attribute of the target stated in the web page or an attribute description pattern used to describe the attribute of the target; an attribute extracting unit that extracts the attribute-related term of the attribute matching the attribute description pattern, from the plurality of web pages; and an attribute description pattern extracting unit that extracts the attribute description pattern matching the attribute-related term from the plurality of web pages.