Number of Steps Measuring Device, Method, and Program

A first calculation unit synthesizes respective measured values of acceleration of an X-axis, a Y-axis and a Z-axis measured by a measurement unit and calculates the synthesized acceleration. A second calculation unit calculates acceleration in a body axis direction (vertical direction) of a wearer wearing the measurement unit from the respective measured values of acceleration of the X-axis, the Y-axis and the Z-axis. The third calculation unit calculates amplitude of a time variation of acceleration in the body axis direction calculated by the second calculation unit. A reference setting unit sets a reference time for determining one step based on the amplitude calculated by the third calculation unit. A walking detection unit detects one-step walking motion of the wearer, a one-step time of which falls within a range of the reference time based on the synthesized acceleration.