Method for estimating step length and portable termianl therefore

A user's step estimation method and a portable terminal therefor are provided to measure a mobile distance and the quantity of motion more exactly by automatically changing algorithm when a user is jogging or walker navigation is conducted by using an accelerometer, thereby exactly and conveniently offering information to the user. An accelerometer(20) senses and outputs an acceleration signal from more than one axis. A user's walking detector(32) calculates an acceleration distributive value from the outputted signal. A motion state decider(34) decides whether the distributive value is larger than a motion state decision threshold value, and if so, the decider(34) decides that a user is running. If the distributive value is smaller than the threshold value, the decider(34) decides that the user is walking. A user's step estimator(36) uses different step estimation algorithms according to the user's motion state.