PROBLEM TO BE SOLVED: To provide a device for appropriately shortening time required for transmitting a measurement result by an activity monitor from the activity monitor to an external apparatus.SOLUTION: An activity monitor 1 which generates activity amount information showing an activity amount related to body motion of a user and transmits it to external apparatuses 3, 4 has a configuration comprising: an acceleration sensor for generating body motion information showing the users body motion a CPU for calculating a unit activity amount, which is an activity amount of the user per unit time, for each unit time on the basis of the body motion information, and generating the activity amount information for each unit time with a data amount depending on magnitude of the unit activity amount and a communication interface for transmitting the activity amount information to the external apparatuses 3, 4.
