TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Device: The first U-shaped plate member, the second U-shaped plate member and a thermal insulating layer are arranged in this order from the outside towards the power generation chamber in the thickness direction, at least part of one of the cathode gas flow passage and the exhaust gas flow passage is formed by the thermal insulating layer and the second U-shaped plate member, and at least part of the other one of the cathode gas flow passage and the exhaust gas flow passage is formed by the first U-shaped plate member and the second U-shaped plate member. The housing includes a third U-shaped plate member formed in a U-shape and including a third upper surface opening portion opening upwardly, two third side walls facing each other, a third bottom wall connecting a lower portion of each of the two third side walls to each other, the first U-shaped plate member, the second U-shaped plate member and the third U-shaped plate member are arranged from the outside towards the power generation chamber in the thickness direction, the housing is formed by layering the first U-shaped plate member, the second U-shaped plate member and the third U-shaped plate member with one another in the thickness direction thereof in a manner that the first upper surface opening portion, the second upper surface opening portion and the third upper surface opening portion are positioned at the upper side in the height direction of the housing, at least part of one of the cathode gas flow passage and the exhaust gas flow passage includes a first side clearance flow passage formed by one of the two first side walls and one of the two second side walls which faces the one of the two first side walls, and a first bottom clearance flow passage formed by the first bottom wall and the second bottom wall which face each other, the first bottom clearance flow passage is in fluid communication with the first side clearance flow passage, and at least part of the other one of the cathode gas flow passage and the exhaust gas flow passage includes a second side clearance flow passage formed by one of the two second side walls and one of the two third side walls which faces the one of the two second side walls, and a second bottom clearance flow passage formed by the second bottom wall and the third bottom wall which face each other, the second bottom clearance flow passage is in fluid communication with the second side clearance flow passage. The fuel cell apparatus further comprises a combusting portion provided above the stack and combusting a combustible gas, the combustible gas including an anode off-gas and/or a fuel gas which are discharged from an upper surface of the stack. The first U-shaped plate member, the second U-shaped plate member and the third U-shaped plate member are arranged in this order from the outside towards the power generation chamber in the thickness direction, at least part of one of the cathode gas flow passage and the exhaust gas flow passage is formed by the first U-shaped plate member and the second U-shaped plate member, and at least part of the other one of the cathode gas flow passage and the exhaust gas flow passage is formed by the second U-shaped plate member and the third U-shaped plate member. At least one of the first U-shaped plate member and the second U-shaped plate member includes protrusions that form the side clearance flow passage and the bottom clearance flow passage by protruding toward the other one of the first U-shaped plate member and the second U-shaped plate member.