This paper describes a new method of measuring position of running user for location-based services in wide indoor environments, such as augmented reality navigation system with wearable computer. Conventional localization methods usually employ a hybrid approach in which user's position is estimated bv combining positioning infrastructures and a pedometer. Since the installation cost of infrastructures increases when the area expands, the measurement Figure Illustration summing up step method of user's relative position with high accuracy is required. Although a numder of methods using a pedometer have been developed to improve the estimation accuracy, these methods generally can handle only usual walking behavior of a user. This paper proposes a new real time localization method for both walking and running users by using a wearable electromagnetic tracker and an inertial sensor. The proposed localization method estimates a moving distance in the period when both legs do not ground by estimating a velocity of waist when user's leg leaves. Experiments have been carried out using a prototype system to evaluate the accuracy of user localization with the proposed