PROBLEM TO BE SOLVED: To accurately determine acceleration caused by forward movement of a person without attaching hardware except an acceleration sensor to the person.SOLUTION: From an acceleration sensor which is attached to a person and the posture of which changes with the forward movement of the person, the z-axis direction acceleration component Aand the y-axis direction acceleration component Aduring the forward movement are obtained, a waveform representing the time change of the physical quantity specified by the A, A, and a gravitational acceleration g is determined, and a vertical acceleration component acaused by the person's forward movement is calculated as the vibrational component of the waveform. For example, based on a relational expression ∫(A+A-g)dt=∫(a+a)dt-2 g∫adt, the (left side) which continues to increase with vibration with respect to time t is determined from the output, etc. from the acceleration sensor, the (first term of right side) which continues to increase with r
