1. A digital information analysis system, comprising: at least one hardware processor in electrical communication with at least one storage device, the storage device storing a digital information analysis program that is executed by the at least one hardware processor, the digital information analysis program comprising: a target selection unit that selects target digital information to be investigated which is stored in an information processing apparatus; a combination storage unit that stores each of a plurality of word combinations related to a predetermined specific item, each of the word combinations consisting of one word having a word class and another word having another word class; a search unit that searches whether the plurality of word combinations stored in the combination storage unit are included in the target digital information selected by the target selection unit; a determination unit that in a case where an order between the one word and the other word in each of the plurality of word combinations included in a sentence is a predetermined order, evaluates a state of the each of the word combinations that comes out in the sentence based on a frequency in which the each of the word combinations whose order of word classes between the one word and the other word is the predetermined order comes out in the target digital information; a relation determination unit that determines a relation of the target digital information to the predetermined specific item on the basis of the frequency, the relation determination unit including: an analysis unit that performs morphological analysis on the target digital information, a positional information giving unit that gives positional information in a sentence indicated by the target digital information to each of the two words forming the word combination, on the basis of an analysis result of the analysis unit; a distance calculation unit that calculates a distance between the positional information of the one word and the positional information of the other word which are given by the positional information giving unit, and a distance relation determination unit that determines the relation on the basis of the distance; and a determination result setting unit that associates a determination result of the relation determination unit with the target digital information.