A living body-attachable electrode includes a substrate that has a first main surface and a second main surface and is made of a material having stretchability, a first electrode pair that is formed on/in the first main surface and includes two opposite electrodes, a second electrode pair that is formed on/in the first main surface and includes two opposite electrodes sandwiching the first electrode pair, and a plurality of gel electrodes that are formed on the second main surface and are in a one-to-one correspondence with the electrodes in the first and second electrode pairs. Each of the electrodes in the first and second electrode pairs and corresponding one of the gel electrodes are electrically connected to each other via a plurality of via conductors penetrating through the substrate.
