The minute-by-minute stepping rate (MMSR) is a unique index of the walking speed. The MMSR under free-living conditions remains unclear.The purpose of the present investigation was to clarify the physical activity (PA) levels based on MMSR under free-living conditions.A total of 85 female volunteers, age from 21 to 91 year, wore a pedometer with a uni-axial accelerometer (Lifecorder, Kenz, Japan) for 7 days consecutively in order to determine the number of steps, the intensity of PA (light intensity PA; LPA, moderate intensity PA; MPA, and vigorous intensity PA; VPA), and the MMSR. Thereafter, the daily time spent in PA at <100, 100 to 129, and 130 stepsmin −1 (minday −1 ) was calculated. All experiments were conducted in March 2007.The number of steps, the time spent in LPA, MPA, VPA, PA at <100, 100 to 129, and 130 stepsmin −1 were 9275±3453 stepsday −1 , 71±25minday −1 , 34±22minday −1 , 4±6minday −1 , 295±88minday −1 , 16±12minday −1 , and 4±6minday −1 . The time spent in PA at <100 stepsmin −1 positively associated with age (p<0.05). The time spent in PA at 100 to 129 stepsmin −1 negatively associated with age (p<0.01).The time spent in PA at <130 of stepsmin −1 MMSR differs across different age-groups under free-living conditions in female adults. The clinical significance with regards to the age-associated changes in MMSR remains unclear.