Method of distance detection using response time of the bluetooth and method of protecting loss using the same, potable device using the same

A distance detection method in accordance with response time between Bluetooth devices, a loss prevention method based on the detection method, and a portable terminal using the prevention method are provided to calculate a distance between the Bluetooth devices by considering a probability rate of separation in accordance with the current response time and maximum response time between the devices, thereby finding a lost portable terminal in a short time. A display unit(120) displays a list of target clients, and displays an identifier of a lost target client and a probability of loss according to decided results of loss. An audio processor(130) generates an alarm according to the decided results. A key input unit(140) generates a key signal necessary for control and activation of a loss prevention function. A memory(150) stores the list of the target clients, and stores threshold data in accordance with response time of the target clients. A controller(160) decides whether a target client is lost, by comparing the second response time with the first response time.