Polarized THz radiation is increasingly being investigated and applied in the new interdisciplinary field “TeraNano.” We report the generation of terahertz (THz) radiation by a linearly polarized femtosecond optical pulse in black phosphorus (BP) crystallites grown by chemical vapor deposition. Characterization of THz radiation is performed by time-resolved THz spectroscopy. It was found that BP emits elliptically polarized THz radiation with an ellipticity of ε  =  0.77  ±  0.03. A saturation was found in the dependence of the THz intensity on the intensity of the incident optical pump for the latter higher than 6  mJ  /  cm². The results of our work can provide new fundamental knowledge needed to create detectors and generators based on BP in the THz range.