Disclosed are an apparatus and method for reconstructing a transmitted file with high performance in real time, which select analysis target packets for reconstruction by first checking using hardware whether data file-related information is present in packets transmitted via large-capacity traffic over a broadband network, and which reconstruct a file in real time only from the selected analysis target packets. The file reconstruction apparatus for reconstructing a data file from packets on a network includes a packet monitoring unit for extracting packets on the network, a collected packet selection unit for determining whether, for the extracted packets, each packet is a reconstruction target based on flow information, and selecting a reconstruction target packet, and a file reconstruction unit for performing file reconstruction by extracting data from the reconstruction target packet and by storing the extracted data as data of a reconstructed file in a relevant flow.