A wireless blood glucose meter (2) has a blood glucose level detector (21), a transmitter (22), a receiver (23), a storage component (24), and a transmission power determiner (25). Whether or not an acknowledge signal has been received and the transmission power when the transmitter (22) has transmitted a blood glucose level are stored as history information in the storage component (24), and the transmission power determiner (25) determines the transmission power when the transmitter (22) transmits on the basis of the history information stored in the storage component (24).