1. A learning device comprising: an input receiving unit that receives an input of first data representing a sentence, rear boundaries of elements having an anaphoric relation within the sentence, and a correspondence relation between a first element that is an antecedent and a second element that is an anaphor; an inferring unit that infers a range of the first element and a range of the second element that are determined by front boundaries and the rear boundaries by inferring the front boundaries of the first element and the second element based on the first data and a predetermined rule; and a learning unit that learns criteria used for determining whether or not there is the anaphoric relation in an arbitrary sentence based on the range of the first element and the range of the second element.