Provided is a threshold determining device for determining a threshold, at which the false matching rate of each data to become less than a required value becomes a required assurance value or more. The threshold determining device comprises an individual threshold evaluation unit, an individual threshold distribution evaluation unit, and an overall threshold determination unit. The threshold determining device determines a similarity of each data to others for each data, determines the threshold of the similarity satisfying a predetermined false matching rate, for each data, determines an individual threshold distribution of the data for each threshold on each of the data, and determines the threshold common to the entire data, as overall data on the basis of the individual threshold distribution.