A stacking-type header (2) according to the present invention includes: a first plate-shaped unit having a plurality of first outlet flow passages (11 A) formed therein; and a second plate-shaped unit (12) stacked on the first plate-shaped unit (11), the second plate-shaped unit (12) having a distribution flow passage (12A) formed therein, the distribution flow passage (12A) being configured to distribute refrigerant, which passes through a first inlet flow passage (12a) 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), in which the distribution flow passage (12A) includes a branching flow passage (12b) including: an opening port configured to allow the refrigerant to flow thereinto; a first flow passage communicating between the opening port and an end portion positioned on an upper side relative to the opening port; and a second flow passage communicating between the opening port and an end portion positioned on a lower side relative to the opening port, and in which the branching flow passage (12b) is smaller in difference in flow resistance between the first flow passage and the second flow passage than a branching flow passage in a state in which a flow-passage resistance in the first flow passage and a flow-passage resistance in the second flow passage are equal to each other, and in a state in which the first flow passage and the second flow passage are point symmetric with each other about the opening port.