FUEL CELL STACK

A coolant flow field of a fuel cell stack includes a power-generation-portion-cooling flow path including a portion overlapping a power generation section of a membrane electrode assembly, a bypass flow path provided on outer peripheries of separators, a main supply flow path extending from a coolant supply passage through the bypass flow path and communicating with the power-generation-portion-cooling flow path, and a bubble release flow path extending from an upper portion of the coolant supply passage in the gravity direction toward the bypass flow path and communicating with the bypass flow path, wherein the bubble release flow path extends upward in the gravity direction above the coolant supply passage.