<；P>；PROBLEM TO BE SOLVED: To accurately detect body movement to obtain accurate count of the body movement. <；P>；SOLUTION: Magnitude of vertical acceleration is obtained, and a lower chord peak value wherein the magnitude changes over from a decrease tendency to an increase tendency and an upper chord peak value wherein the magnitude changes over from the increase tendency to the decrease tendency are detected. A difference between the detected lower chord peak value and upper chord peak value is calculated. The calculated difference is compared with a threshold value, it is decided that the body movement is detected when the difference is the threshold value or above, and a body movement detection flag is turned on. It is decided that the body movement is not detected when the difference is smaller than the threshold value, and the body movement flag is kept turning off. <；P>；COPYRIGHT: (C)2009,JPO&INPIT
