To provide a structure of an underground pile which enables a sensor to be insertably/extractably installed in the underground pile and facilitates the correction of measurement values by the sensor that is insertably/extractably installed.

The structure of the underground pile 1 having the sensor therein has the underground pile 1 constructed in the ground by the solidification of a solidification material 2, a protective pipe 3 embedded in the solidification material 2 for forming a space in the length direction of the underground pile 1, and the sensor which is extractably inserted into the space of the protective pipe 3.