Repeated mild head trauma, specifically concussion, is a risk factor in contact sports such as judo, soccer, and American football. Concussion is a transient disturbance of the consciousness with no clear abnormality on computerized tomography or magnetic resonance imaging, and repeated trauma can cause psychiatric symptoms such as cognitive impairment and depression. Transcranial direct current and deep brain electrical stimulations have been reported to recover movement, consciousness, and cognitive disorders in patients with sequelae of head trauma. However, the mechanism of neuroplasticity induced by the brain stimulation has not been comprehended completely. In this study, we focused on the formation of neural circuits, which is important for the recovery of high brain functions, and we investigated the effectiveness of electrical stimulation on the mechanically injured neurites. Neurons were isolated from the cerebral cortexes of fetal rats and mechanically injured by cutting neurites using a micropipette. Neurite outgrowth was measured via microscopic observation under the following conditions: no electrical stimulation group with mechanical injury (Control), electrical stimulation group with 300mV/mm, 20Hz, and 15 min for 3 days before (Pre) or after (Post) mechanical injury, and electrical stimulation group for 3 days before and 3 days after mechanical injury (Pre-Post). When the neurite length after mechanical injury was less than 450μm, the neurite lengths at day 3 were 650±60μm in Control, 851±111μm in Pre, 975±135μm in Post, and 929±128μm in Pre-Post. Conversely, when the neurite length after mechanical injury was greater than 450μm, the neurite lengths at day 3 were 864±69μm in Control, 1419±137μm in Pre, 1236±128μm in Post and 1458±145μm in Pre-Post. These results indicate that electrical stimulation before injury promotes neurite outgrowth after injury. The stimulation effect decreased after 2 days but continued electrical stimulation after the injury could promote neurite outgrowth continuously. The results suggest that electrical stimulation has a protective effect on the brain, and it promotes the regeneration of neural circuits after brain injury.