An entomopathogenic bacterium, Xenorhabdus nematophila, induces an immunosuppression of target insects by inhibiting phospholipase $A_2$ ($PLA_2$) activity. Recently, an immune-associated $PLA_2$ gene was identified from the red flour beetle, Tribolium castaneum. This study cloned this $PLA_2$ gene in a bacterial expression vector to produce a recombinant enzyme. The recombinant T. castaneum $PLA_2$ ($TcPLA_2$) exhibited its characteristic enzyme activity with substrate concentration, pH, and ambient temperature. Its biochemical characteristics matched to a secretory type of $PLA_2$ ($sPLA_2$) because its activity was inhibited by dithiothreitol (a reducing agent of disulfide bond) and bromophenacyl bromide (a specific $sPLA_2$ inhibitor) but not by methylarachidonyl fluorophosphonate (a specific cytosolic type of $PLA_2$). The X. nematophila culture broth contained $PLA_2$ inhibitory factor(s), which was most abundant in the media obtained at a stationary bacterial growth phase. The $PLA_2$ inhibitory factor(s) was heat-resistant and extracted in both aqueous and organic fractions. Effect of a $PLA_2$-inhibitory fraction on the immunosuppression of T. castaneum was equally comparable with that resulted from inhibition of the $TcPLA_2$ gene expression by RNA interference.