An encrypted-traffic discrimination device includes an input interface, a flow discrimination section, a data accumulation section, a selective data calculation section, a calculation result determination section, and an output interface. The flow discrimination section discriminates the input traffic into separate flows based on at least a transmission origin address and a transmission destination address. The data accumulation section accumulates characteristic amount data of the traffic for each of the separate flows. The selective data calculation section executes an evaluation computation utilizing specific data from the characteristic amount data. The calculation result determination section that, based on a calculated evaluation computation value, executes threshold value determination to determine whether or not the traffic is encrypted, and, if the traffic is determined to be encrypted, which encryption format the traffic is encrypted with.