Simplified gait analysis system using wearable sensors based on accelerometers and gyroscopes were focused in this study for rehabilitation of motor function and daily exercise for health. In this paper, a preliminary test of stride length estimation for each step using an accelerometer and a gyroscope attached on the foot was performed with two neurologically intact subjects. Reference signals were obtained from 3D motion analysis system. Although error in stride length estimation varied between subjects and between trials, mean absolute error was acceptable (less than about 10%) except for the 1st step (start of walking) of one subject. For subject B, the mean absolute errors for the 2nd step were less than 5% for all the trials. Experimental results also suggested that precise measurement of tilt angle of the foot and determination of appropriate integration period would realize practical estimation of the stride length using only inertial sensors. Since the sensor unit used in the experiment was not packaged all in one, development of a sensor unit and further tests with the developed sensor would be in the next work.