An evaluation apparatus that is connected to a bus used by a plurality of electronic control units that constitute an electronic control system for communication and that evaluates security of the electronic control system. The evaluation apparatus includes a transmitter that sends, to the bus, at least one attack frame including an invalidation frame for invalidating a frame on the bus, a monitor that monitors at least one of the plurality of electronic control units, and an evaluator that evaluates the electronic control system in terms of security on the basis of the result of monitoring performed by the monitor when the attack frame is sent from the transmitter to the bus.