A bacterial expression vector for the human foamy virus (HFV) integrase was constructed and expressed in Escherichia coli. By two-step purification using a nickel-chelated column and a SP-sepharose chromatography; the HFV into-grase protein of 43 kDa was purified to near homogeneity, and used to investigate biochemical characteristics of the enzymatic activities, such as endonucleolytic and disintegration activities. Oligonucleotide substrates were specifically and efficiently cleaved by the purifed HFV integrase in the presence of Mn $^{+2}$, but not in the presence of Mg $^{+2}$, indicating that the HFV integrase is not able to use Mg $^{+2}$ as a cofactor Endonucleolytic reaction was almost completed in 60 min at 37 $^{circ}C$. In addition, the maximum enzymatic activities were observed at 5 mM Mn $^{+2}$ in the buffer of which pH was from 7.0 to 9.0. The endonucleolytic activities were dose-dependently blocked in the addition of baicalein or chicolic acid which is a well-known inhibitor of human immunodeficiency virus integrase.