A fuel cell 100 is characterized by including an electrolyte 30, and an electrolyte-strengthening member 10 that has a penetration portion 11 and strengthens the electrolyte. The electrolyte 30 has a high-electrical-current-density region of which electrical current density is higher than an average electrical current density of the electrolyte 30 and has a low-electrical-current-density region of which electrical current density is lower than the average electrical current density, at a face thereof on an opposite side of the electrolyte-strengthening substrate 100. An area where the penetration portion 11 faces with the high-electrical-current-density region is larger than that where the penetration portion 11 faces with the low-electrical-current-density region.