A stacking-type header (2) according to the present invention includes: a first plate-shaped unit (11) having formed therein a plurality of first outlet flow passages (11A) and a plurality of first inlet flow passages (11 B); and a second plate-shaped unit (12) stacked on the first plate-shaped unit (11), the second plate-shaped unit (12) having formed therein: at least a part of a distribution flow passage configured to distribute refrigerant, which passes through a second inlet flow passage to flow into the second plate-shaped unit (12), to the plurality of first outlet flow passages (11A) to cause the refrigerant to flow out from the second plate-shaped unit (12); and at least a part of a joining flow passage configured to join together flows of the refrigerant, which pass through the plurality of first inlet flow passages (11 B) to flow into the second plate-shaped unit (12), to cause the refrigerant to flow out toward a second outlet flow passage, in which the first plate-shaped unit (11) or the second plate-shaped unit (12) comprises at least one plate-shaped member having formed therein: a flow passage through which the refrigerant passes to flow into the plurality of first inlet flow passages (11 B); and a flow passage through which the refrigerant passes to flow into the second inlet flow passage (11 B), and in which the at least one plate-shaped member has a through portion or a concave portion formed in at least a part of a region between the flow passage through which the refrigerant passes to flow into the plurality of first inlet flow passages (11 B) and the flow passage through which the refrigerant passes to flow into the second inlet flow passage.