A received data processing system is composed of a transmitter which includes a transmission unit which sends by radio sensor data such as a pulse rate obtained by a pulse sensor, a wrist watch which receives the sensor data from the transmitter using a reception unit and displays it on a display, and an external storage attached removably to the wrist watch for storing the received sensor data. Since the transmitter is attached closely to the human body to sense a pulse rate, detection of the pulse rate is ensured even if the user is in exercise. Since data on the pulse rate is stored in the removable external storage through the wrist watch, the system can process a large amount of data.