A wireless blood glucose meter (2) is a battery (26)-powered apparatus to communicating wirelessly with a portable terminal (3), and includes a blood glucose level detector (21) that measures a blood glucose level, a transmitter (22) that transmits the blood glucose level measured by the blood glucose level detector (21) to the portable terminal (3), a receiver (23) that receives a response signal sent from the portable terminal (3) in response to the transmission of the blood glucose level by the transmitter (22) to the portable terminal (3), and a voltage monitor (24) that monitors the output voltage of the battery (26). A transmission control circuit (231) changes the transmission method used by the transmitter (22) on the basis of the output voltage of the battery (26) as detected by the voltage monitor (24).
