A method and apparatus of a portable terminal estimate a step length of a pedestrian. An accelerometer detects acceleration caused by a movement of the portable terminal as a pedestrian carrying the portable terminal walks. A gyroscope detects angular velocity caused by the movement of the portable terminal as the pedestrian walks. A controller determines a magnitude of a swinging motion of the portable terminal by using at least one of the detected acceleration and angular velocity, determines that the portable terminal makes the swinging motion when the magnitude of the swinging motion is equal to or greater than a predetermined value, determines a carrying position of the portable terminal in the pedestrian's body by using at least one of the detected acceleration and angular velocity, and estimates a step length of the pedestrian according to the determined carrying position of the portable terminal.