The purpose of this study is to investigate the effect of P300 latency in case of magnetic stimulation to human brain by rTMS. This stimulation is 100 pulses with 1 Hz or 0.5 Hz low-frequency. The stimulation points are left-right SMG and left-right DLPFC. In case of 1 Hz magnetic stimulation to left SMG, P300 latency after the magnetic stimulation was shorter than P300 latency before the magnetic stimulation. In case of 1 Hz low-frequency magnetic stimulation to left DLPFC, P300 latency after the magnetic stimulation was later than before the magnetic stimulation. In case of 0.5 Hz low-frequency magnetic stimulation to left SMG, the delay of P300 latency was observed. Generally, in the low-frequency magnetic stimulation equal to or less than 1 Hz, the brain activity is inhibited by stimulating the brain. The activity of left SMG is excited at 1 Hz and inhibited at 0.5 Hz. As this reason, at first, in this study, the frequency of the magnetic stimulation is just 1 Hz and this frequency is border of low-frequency and high-frequency. Secondarily, the sensitivity for the magnetic stimulation varies by parts of brain. Therefore, this study suggests that left SMG is activated by the short-term magnetic stimulation using rTMS (1 Hz, 100 pulses).