According to a photobiomodulation method and system for inducing the activity of a brain-derived nerve growth factor in a hippocampal tissue, proposed by the present invention, a photobiomodulation (PBMT or PBM) method, which is a therapy using infrared to seat-infrared (wavelength of 600-1100 nm) light, is utilized, thereby delaying the death of cells, promoting the proliferation of meristematic cells, and inducing natural treatment without the risk of adverse reactions to a disease or lesion, in a simple and easy manner in which low-level laser light is irradiated into a living body, based on the principle that certain molecules in the living body can absorb photons and trigger signaling pathways in response to light of a specific wavelength band.