A fuel cell apparatus includes a stack of fuel cells, first and second end plates disposed at opposite ends of the stack of fuel cells to press the stack of fuel cells and being connected by a fastening member, and a pressure plate disposed inboard of the first end plate. A concave portion is formed at an inboard surface of the first end plate and a convex portion is formed at an outboard surface of the pressure plate. The convex portion contacts the concave portion. The first and second end plates are coupled to the fastening member (or, a tension plate) by a serration and a bolt. An adjusting portion is formed in the first end plate, and the concave portion is formed in the adjusting portion. A load variance decreasing mechanism is disposed in series with the contact portion of the convex portion and the concave portion. A recess is formed in an electrical insulator disposed inboard of the pressure plate, and the pressure plate is disposed in the recess. The convex portion may include a spherical surface or a cylindrical surface. The load variance decreasing mechanism may include a plurality of sets of coned disk springs disposed in series with each other. The fuel cell apparatus may include an attaching member constituting a portion of the fuel cell apparatus and attaching the fuel cell apparatus to a vehicle.