An apparatus and method for storing data traffic on a flow basis. The apparatus for storing data traffic on a flow basis includes a packet storage unit, a flow generation unit, and a metadata generation unit. The packet storage unit receives packets corresponding to data traffic, and temporarily stores the packets using queues. The flow generation unit generates flows by grouping the packets by means of a hash function using information about each of the packets as input, and to store the flows. The metadata generation unit generates metadata and index data corresponding to each of the flows, and stores the metadata and the index data.