The present invention suppresses charges incurred by data communications. A controller transmits data values acquired by sensors to a data center at predetermined intervals. When a predetermined interval has elapsed, a data value to be transmitted is compared with the previously transmitted data value, and in the absence of a change that is equal to or more than a predetermined variation amount, this data value is not transmitted. When such a state in which data values are not transmitted continues for a predetermined interval or more, the data value is transmitted irrespective of the data value variation amount. Further, when the data value has changed abruptly, the data value is transmitted even if the predetermined interval has not yet elapsed. The present invention can be applied to a controller that transmits data values acquired by sensors to a data center for collecting these data values.