An arrester includes a switch and a lightning detection breaker connected to the switch. The lightning detection breaker includes a metal conducting terminal electrically connected to an earth return, a DC power supply terminal, a ground terminal and an output terminal. When the power supply is under a lightning strike, a potential difference of both the DC power supply terminal and the ground terminal of the lightning detection breaker will go up to several thousands of volts. However, a voltage of the metal conducting terminal will not go up because the metal conducting terminal is electrically connected to the earth return. The switch will automatically become open circuit by the lightning detection breaker, and therefore an electronic device connected to the arrester is protected from damage done by the lightning.