Transcranial magnetic stimulation (TMS) is a non-invasive method for modulating neurons in the brain. The technique has been investigated for a variety of diagnostic and therapeutic applications for neurological disorders such as Parkinson's disease and Post-Traumatic Stress Disorder (PTSD). TMS treatment has been approved by US Food and Drug Administration for the treatment of depression; however, the effect of TMS on individual neurons is least understood. We first carried out the experiment to investigate the effect of magnetic field on the growth rate of neuronal cells. N27 cell is one type of dopaminergic neuronal cells from the brain of mice. We first cultured the cells in the incubator. After that, we used the air-cooled double coil to treat them at specific growing period with short pulses of time varying magnetic field. Each treatment was 30 minutes long. We counted the number of cells 24 hours after the TMS treatment to ensure enough time was given to see the effect on the growth of N27 cells. After using three different cell counting methods, we found the grow rate of N27 cells increased with upward oriented magnetic field treatment while it decreased with downward oriented magnetic field treatment.