Pathogenic pain is a common sign of many diseases. The mechanism is unclear. Activating transcription factor 4 (ATF4) plays a critical role in cell activation. Brain-derived neurotrophic factor (BDNF) is an important molecule in pathogenic pain. This study aims to investigate the role of ATF4 in inducing BDNF release from microglial cells. In this study, mouse microglial cells were cultured. The levels of BDNF in the culture medium were determined by enzyme-linked immunosorbent assay. Overexpression of ATF4 in microglial cells was performed by gene transfection. The apoptosis of microglial cells was assessed by flow cytometry. The results showed that microglial cells expressed ATF4 and protease-activated receptor-2 (PAR2). BDNF was detectable in the culture medium of microglial cells, which was significantly increased in the ATF4-overexpressing microglial cells. The ATF4-overexpressing microglial cells showed a high frequency of apoptotic cells, which could be inhibited by exposure to the PAR2 agonist tryptase in the culture. The tryptase-treated ATF4-overexpressing microglial cells kept higher secretion of BDNF. We conclude that the activation of ATF4 can increase BDNF release from microglial cells.