1. An information analysis apparatus for performing an analysis on text information to determine whether or not the text information corresponds to target information, comprising: a density estimation unit that estimates, in units of analysis each composed of a plurality of sentences of the text information, a density indicating a degree to which each unit of analysis contains the target information; and a determination unit that obtains an evaluation value indicating a degree to which each sentence included in each unit of analysis corresponds to the target information from the estimated density of the unit of analysis, and determines whether or not the sentence is the target information based on the evaluation value.