There are provided a sensor device and a detecting method employing the same, with which it is possible to carry out measurement using a simple operation and to reduce damage. A sensor device includes a liquid sample sensor and a reader in which the liquid sample sensor is detachably mounted. The liquid sample sensor includes a sensor main body including a first face, a sensor element located in the sensor main body, and a plurality of external terminals located on the first face of the sensor main body. Four external terminals are each located at corresponding one of four corners of the rectangular shaped first face, and a pattern of placement of the four external terminals exhibits two-fold rotational symmetry.