PROBLEM TO BE SOLVED: To provide an active mass measuring system, an information terminal, an active mass measuring method, and a program capable of achieving power saving, miniaturization and cost reduction of an active mass meter.SOLUTION: An active mass measuring system includes an active mass meter 10 and an information terminal 20. The active mass meter 10 is configured so as to wirelessly transmit active mass data of a user to the information terminal 20, and the information terminal 20 is configured so as to set communication frequency on the basis of an activity state of the user, and cause the active mass meter 10 to transmit the active mass data at the set communication frequency. By the active mass measuring system like this, the communication frequency is set on the basis of the activity state of the user and the active mass meter 10 can be caused to transmit the active mass data at the set communication frequency. Thereby, the communication frequency can be switched according to the activity state of the user without providing a manual switch to the active mass meter 10, and in consequence, power saving, miniaturization and cost reduction of the active mass meter 10 can be achieved.
