The amulet is a children's safety warn device. It has two parts: the master and the sub-machine. The children who wear the sub-machine, when they get closely to the strong electric field, electric radiation, into the water, sleep, syncope, or too far away from the adults, the sensor will receive these dangerous information through the wireless radio sent to the master .Then it will warn (alert) and flash signal. Press the switch contact of the sub-machine also can make the master warn. In the emergency, the sub-machine can be used as an alarm whistle.