A packet storage method includes receiving a plurality of packets from a network including a plurality of connections, associating, with each of the packet, a connection via which the corresponding packet has passed, specifying a connection, among the plurality of connections, in which an error has occurred, based on analysis of the plurality of packets, identifying the packet which has passed through the connection in which the error has occurred, and storing, in a storage device, the identified packet, among the plurality of received packets.