A sensor capable of simply and quickly measuring the electrical activities of a number of cells simultaneously and a device comprising the sensor and capable of detecting the signal transmission between subject cells are provided. The sensor comprises a plurality of electrodes provided on a substrate. The electrodes individually measure a signal generated by a biological sample held by each of the electrodes. Each of the electrodes comprises a depression for holding the biological sample, a throughhole which is in communication with the depression and penetrates to a rear side of the substrate, an electrode portion, and a drawing line from the electrode portion. The electrodes are arranged so that the samples held by the depressions electrically communicate with one another.