Abstract: A sensor such as for sensing dissolved oxygen in plural cells spaced apart from each other by a predetermined distance includes projection sections provided at intervals spaced according to the predetermined distance on an edge section of a plate shape base body. At least an active electrode and a counter-electrode are at predetermined positions on each projection section, and lead-out terminals are provided at predetermined positions on the substrate facing the substrate portion where the projection sections are formed. The substrate has wiring electrically connecting both the active electrodes and the counter-electrode to the lead-out terminals. This arrangement greatly reduces measurement labor and variance in measurement data results. In addition, it increases the number of objects that can be measured during a measurement operation.