17. The information analysis apparatus according to claim 12 , further comprising: a determination model learning unit, wherein the density estimation model learning unit further estimates, for each unit of training, a density indicating a degree to which the unit of training contains the target information, the determination model learning unit generates feature data from the density estimated by the density estimation model learning unit and the training data, and further learns a determination model usable in the determination performed by the determination unit, using the feature data, and the determination unit determines whether or not each sentence is target information in accordance with the learned determination model.
17. The information analysis apparatus according to claim 12 , further comprising: a determination model learning unit, wherein the density estimation model learning unit further estimates, for each unit of training, a density indicating a degree to which the unit of training contains the target information, the determination model learning unit generates feature data from the density estimated by the density estimation model learning unit and the training data, and further learns a determination model usable in the determination performed by the determination unit, using the feature data, and the determination unit determines whether or not each sentence is target information in accordance with the learned determination model. 18. The information analysis apparatus according to claim 17 , wherein the density estimation model learning unit further estimates, for each unit of training, a density indicating a degree to which the unit of training contains the target information, using the learned density estimation model.