Provided is a technology that reduces the amount of biometric data sent. A data processing device comprises a biometric data acquisition unit that acquires biometric data of a subject； a sending condition acquisition unit that acquires a sending condition that comprises a first time period and associated with a health-related characteristic of the subject； a data classification unit that determines whether a measurement time of the biometric data is within the first time period, classifies the biometric data as data for sending when a determination result indicates that the measurement time is within the first time period, and classifies the biometric data as data not for sending when the determination result indicates that the measurement time is within a second time period, which is different from the first time period； and a data output unit that outputs the data for sending.
