An attack communication detection device that is robust against a deviation from the design value of a communication interval is provided. The attack communication detection device is an attack communication detection device that detects an attack communication from a communication of each electronic control unit in a communication network and includes: a receiving unit that receives communication data for detection which may or may not include an attack communication; a sum-of-communication-intervals calculation unit that calculates the sum of communication intervals, which is the sum of two adjacent communication intervals, of the communication data for detection; an estimated distribution model storage that stores in advance an estimated distribution model of a communication interval and the sum of communication intervals of communication data for learning which does not include an attack communication; and a detection unit that detects whether or not the communication data for detection includes an attack communication based on the estimated distribution model and the sum of communication intervals of the communication data for detection.