There is disclosed a sensor node capable of transmitting and receiving a large amount of data or data desired to be reliable without missing data, while preventing battery exhaustion and unnecessary compression of the transmission bandwidth. A name-tag type sensor node includes a detector for detecting connection of an external power supply. When the detector detects that the external power is supplied, the name-tag type sensor node transmits and receives a large amount of data, such as bulk transmission data, at an increased frequency by means of a data selector, a communication timing controller, and a wireless communication controller. Alternatively, the name-tag type sensor node transmits and receives the data desired to be reliable, such as rewriting data of firmware.