To develop bioflocculant for wastewater treatment, about 60 type culture strains and 450 strains isolated from natural sources were examined for screening their ability to flocculate the swine wastewater. Among them, YWO-5 showed the highest activity for NTU removal efficiency and was identified as Bacillus megaterium according to the cultural, morphological and physiological properties. The maximum production of the flocculant was achieved in culture medium containing 2% glucose, 0.05% soytone, 0.01% $CaCl_2$, 0.05% $KH_2PO_4$, and 0.05% yeast extract with initial pH 6.5 when cultured with rotary shaker controlled at 20$^{circ}C$ and 150 rpm. With jar fermentor, the maximum production was reached to NTU removal efficiency of 93% after 3 days under the optimal conditions. The bioflocculant produced by Bacillus megaterium YWO-5 was effective on various suspended solids and organic wastewaters.