The invention aims at downsizing a sensor node incorporating a biosensor to detect biological information and at improving the accuracy of detection made by the biosensor and ensures a quality of communication performed by the sensor node. In the sensor node, a sensor section with a pulse wave sensor formed therein and a main body section with a data processing unit and a wireless communication unit formed therein are separated. The sensor section includes an A/D converter unit that converts an analog signal corresponding to biological information detected by the pulse wave sensor to a digital signal. Digital signal transmission is performed from the A/D converter unit to the data processing unit. Moreover, in the sensor node, there is no conductive member that planarly overlaps with an antenna.