2. The information analysis apparatus according to claim 1 , further comprising: a unit-of-analysis generation unit that generates a plurality of the units of analysis from the text information, wherein the density estimation unit estimates the density for each unit of analysis generated by the unit-of-analysis generation unit.
5. The information analysis apparatus according to claim 2 , wherein the unit-of-analysis generation unit generates the plurality of units of analysis by, for each unit of analysis, extracting a preset number of consecutive sentences from a plurality of consecutive sentences of the text information and generating the unit of analysis from the extracted consecutive sentences, such that a sentence included in each unit of analysis coincides with a sentence included in another unit of analysis.