Separator for a fuel cell and a fuel cell stack comprising the same

This application relates to a separator for a fuel cell and a fuel cell stack with improved durability, which contains the same, particularly to a solid oxide fuel cell stack. Specifically, this application allows an oxidizer and a fuel to flow in a counter-flow manner and a cross-flow manner in the fuel cell stack by forming an outlet manifold and an inlet manifold to have a specific shape, location and size in the separator. As a result, interlayer peeling, microcracking, etc. are prevented because no variation in temperature, reactant concentration, power, etc. occurs between each unit cell and the power density per unit volume is significantly improved because the volume is minimized.