Gasket for reducing stress concentration in fuel cell stack

Disclosed is a gasket for reducing stress concentration in a fuel cell stack, which prevents damage or deformation of a separator and further prevents a position shift of the gasket by reducing stress concentration formed at a specific region by deformation of the gasket due to a compression force. In particular, the gasket includes a T-shaped or cross-shaped gasket joint to form hydrogen, air and coolant manifolds, and the gasket joint has a structure in which two joint branches forming an angle of 180° in the opposite direction to each other are joined at one point with a particular angles which reduce stress concentration formed due to compression force by deformation of the gasket.