1. A person tracking device comprising: a person region information extraction unit that detects a person region where a person appearing in a video belongs, and generates person region information describing information of the person region; an accompanying person determination unit that identifies at least one accompanying person accompanying a tracking target person among persons included in the person region information based on the person region information and information specifying a tracking target person, and generates accompanying person information describing the accompanying person; a distinctive person selection unit that selects a distinctive person having a salient feature using the person region information among the accompanying person specified by the accompanying person information, and generates distinctive person information describing the distinctive person; and a person tracking unit that calculates a distinctive person tracking result being a tracking result for the distinctive person based on the person region information and the distinctive person information.