Body motion detection device capable of properly managing information on number of steps in walking exercise

A body motion detection device comprising:

• a count unit counting a number of steps in a walking mode by detecting body motion, said walking mode including a first walking mode and a second walking mode;
• a calculation unit calculating an amount of exercise based on said counted number of steps;
• a receiving unit receiving from another device a signal indicating start or end of said second walking mode, said signal containing information identifying said another device;
• and
• a setting unit setting, as a parameter used in said calculation unit, a parameter for said first walking mode when said signal indicates said end of said second walking mode and a parameter for said second walking mode when said signal indicates said start of said second walking mode.