Localization system of under water robots

A location estimating system of an underwater robot according to the present invention includes a location measuring unit which is interlocked to the underwater robot moving according to a dead reckoning sailing system and outputs a depth where the underwater robot is positioned and a movement direction angle of the underwater robot; and a calculation unit which applies a movement estimation value including the depth and the movement direction angle and an odometer of an encoder installed on the underwater robot to an extended Kalman filter and estimates the current location of the underwater robot on a real time basis.