A fuel cell unit comprising a plurality of power-generating elements stacked on top of each other, the power-generating elements each including - a plate-like cell having one principal surface to which an anode is connected and the other principle surface to which a cathode is connected, - an anode plate stacked over and electrically connected to the anode, and - a cathode plate stacked over and electrically connected to the cathode, wherein the cathode plate includes: - a plurality of first gas passages which are adjacent to each other and extend from an end portion of the cell to an opposite end portion of the cell and thereby serve as passages for a gas containing oxygen, and which are each connected to an associated one of air supply ports located near the end portion of the cell and to an associated one of the air exhaust ports located near the opposite end portion of the cell, - a plurality of second gas passages which are sandwiched between the first gas passages and the cell, which are adjacent to each other and extend in a direction intersecting an extending direction of the first gas passages, which are exposed toward the cell, and each of which communicates with at least two of the first gas passages in a vicinity of an intersection in a direction in which the cathode plate is stacked, - a first plate in which the first gas passages are formed, and - a second plate which is stacked on the first plate and in which the second gas passages are formed. - a plate-like cell having one principal surface to which an anode is connected and the other principle surface to which a cathode is connected, - an anode plate stacked over and electrically connected to the anode, and - a cathode plate stacked over and electrically connected to the cathode, wherein the cathode plate includes: - a plurality of first gas passages which are adjacent to each other and extend from an end portion of the cell to an opposite end portion of the cell and thereby serve as passages for a gas containing oxygen, and which are each connected to an associated one of air supply ports located near the end portion of the cell and to an associated one of the air exhaust ports located near the opposite end portion of the cell, - a plurality of second gas passages which are sandwiched between the first gas passages and the cell, which are adjacent to each other and extend in a direction intersecting an extending direction of the first gas passages, which are exposed toward the cell, and each of which communicates with at least two of the first gas passages in a vicinity of an intersection in a direction in which the cathode plate is stacked, - a first plate in which the first gas passages are formed, and - a second plate which is stacked on the first plate and in which the second gas passages are formed. - a plurality of first gas passages which are adjacent to each other and extend from an end portion of the cell to an opposite end portion of the cell and thereby serve as passages for a gas containing oxygen, and which are each connected to an associated one of air supply ports located near the end portion of the cell and to an associated one of the air exhaust ports located near the opposite end portion of the cell, - a plurality of second gas passages which are sandwiched between the first gas passages and the cell, which are adjacent to each other and extend in a direction intersecting an extending direction of the first gas passages, which are exposed toward the cell, and each of which communicates with at least two of the first gas passages in a vicinity of an intersection in a direction in which the cathode plate is stacked, - a first plate in which the first gas passages are formed, and - a second plate which is stacked on the first plate and in which the second gas passages are formed.