An attack detection device executes a process that includes receiving a message periodically transmitted from a communication device in a network, calculating a reception range for receiving a message including identification information in a reference message selected from the received messages by using a transmission period of a message identified by the identification information, the message being transmitted two or more periods after the reference message, storing the reception range associated with an order of reception of a message predicted to be received in the reception range when the reference message is used as a reference, and determining that an attack on the network is detected when a reception time of the received message including the identification information is not within the reception range associated with the order of reception of the received message in a case where the reference message is used as a reference.