A stacking-type header connected to a plurality of tubes (20a, 20b) including a first tube and a second tube and configured to allow inflow of fluid from the first tube and inflow of the fluid into the second tube, comprising: a first plate-like body (11a, 12a) having a plurality of first opening ports, each of the plurality of tubes (20a, 20b) being connected to a corresponding one of the plurality of first opening ports of the first plate-like body (11a, 12a); a plurality of second plate-like bodies (11b to 11d, 12b to 12d) having a plurality of second opening ports, the plurality of second plate-like bodies (11b to 11d, 12b to 12d) being stacked on the first plate-like body (11a, 12a) so that the plurality of second opening ports communicate with the plurality of first opening ports to form flow passages; and one or more third plate-like bodies (11e, 11f, 12e) stacked on the plurality of second plate-like bodies (11b to 11d, 12b to 12d), wherein each of the flow passages has a flow passage area that continuously or gradually changes in a stacking direction of the plurality of second plate-like bodies (11b to 11d, 12b to 12d), the flow passages are provided to correspond to the plurality of tubes (20a, 20b) connected to the first plate-like body (11a, 12a), each of the third plate-like bodies (11e, 11f, 12e) are provided with a connecting flow passage that allows communication between a flow passage corresponding to the the first tube and a flow passage corresponding to the second tube, characterized in that a central axis of each of the plurality of first opening ports and a central axis of each of the plurality of second opening ports of one of the plurality of second plate-like bodies (11d, 12d) that is located farthest away from the first plate-like body (11a, 12a) are eccentric to each other, and a central axis of each of the plurality of second opening ports in the flow passage corresponding to the first tube is eccentric toward the second tube with respect to a central axis of each of the plurality of first opening ports in the flow passage corresponding to the first tube. a first plate-like body (11a, 12a) having a plurality of first opening ports, each of the plurality of tubes (20a, 20b) being connected to a corresponding one of the plurality of first opening ports of the first plate-like body (11a, 12a); a plurality of second plate-like bodies (11b to 11d, 12b to 12d) having a plurality of second opening ports, the plurality of second plate-like bodies (11b to 11d, 12b to 12d) being stacked on the first plate-like body (11a, 12a) so that the plurality of second opening ports communicate with the plurality of first opening ports to form flow passages; and one or more third plate-like bodies (11e, 11f, 12e) stacked on the plurality of second plate-like bodies (11b to 11d, 12b to 12d), wherein each of the flow passages has a flow passage area that continuously or gradually changes in a stacking direction of the plurality of second plate-like bodies (11b to 11d, 12b to 12d), the flow passages are provided to correspond to the plurality of tubes (20a, 20b) connected to the first plate-like body (11a, 12a), each of the third plate-like bodies (11e, 11f, 12e) are provided with a connecting flow passage that allows communication between a flow passage corresponding to the the first tube and a flow passage corresponding to the second tube, characterized in that a central axis of each of the plurality of first opening ports and a central axis of each of the plurality of second opening ports of one of the plurality of second plate-like bodies (11d, 12d) that is located farthest away from the first plate-like body (11a, 12a) are eccentric to each other, and a central axis of each of the plurality of second opening ports in the flow passage corresponding to the first tube is eccentric toward the second tube with respect to a central axis of each of the plurality of first opening ports in the flow passage corresponding to the first tube.