An objective of the present invention is to provide a sensor device which is used by being attached to a lifeform, and which is capable of easily and reliably carrying out tracking of a deformation of the surface of the lifeform. This sensor device comprises: a sensor element, further comprising a sheet-shaped first dielectric layer which is formed from an elastomer composite, and a first electrode layer and a second electrode layer which are formed from a conductive composite including carbon nanotubes and which are formed respectively sandwiching the first dielectric layer upon the obverse face and the reverse face of the first dielectric layer so as to be in opposition to one another at least partially, said sensor element deforming reversibly such that the surface areas of the obverse and reverse faces of the first dielectric layer change, with the opposing portions of the first electrode layer and the second electrode layer as a detection part and a measuring device which measures a change in capacitance in the detection part. The sensor device is used by being attached to a lifeform, and is employed in tracking of deformation of the surface of the lifeform.
