In a stacking-type header including a first plate-shaped unit and a second plate-shaped unit, a distribution flow passage in the second plate-shaped unit includes at least one branching flow passage, in which the second plate-shaped unit includes at least one plate-shaped member having a groove formed as a flow passage, the groove having at least one branching portion for branching one branch part into a plurality of branch parts, in which the at least one branching flow passage is formed by closing the groove in a region other than a refrigerant inflow region and a refrigerant outflow region, and in which at least part of the refrigerant branched by flowing into the at least one branching flow passage sequentially passes through the one branch part and the plurality of branch parts, and flows out from the at least one branching flow passage through end portions of the groove.