A stacking-type header, comprising: a first plate-shaped unit having a plurality of first outlet flow passages formed therein; and a second plate-shaped unit being stacked on the first plate-shaped unit and having a first inlet flow passage formed therein and a distribution flow passage formed therein, the distribution flow passage being configured to distribute refrigerant, which passes through the first inlet flow passage to flow into the second plate-shaped unit, to the plurality of first outlet flow passages to cause the refrigerant to flow out from the second plate-shaped unit, wherein the distribution flow passage comprises at least one branching flow passage, wherein the second plate-shaped unit comprises at least one plate-shaped member (23_1) having a groove formed as a flow passage, the groove having at least one branching portion for branching one branch part into two branch parts (23k, 23l), wherein the one branch part extends straight; characterised in that the two branch parts (23k, 231) extend straight in directions opposite to each other and perpendicular to a straight line part of the one branch part, wherein the at least one branching flow passage is formed by closing a region in the groove other than a refrigerant inflow region and a refrigerant outflow region, and wherein at least part of the refrigerant flowing into the at least one branching flow passage sequentially passes through the one branch part and branches at the two branch parts (23k, 23l) into one flow which passes through one of the two branch parts (23k, 23l) and an other flow which passes through the other of the two branch parts (23k, 23l), and wherein the one flow and the other flow each flow out into mutually different flow passages of the plurality of first outlet flow passages. a first plate-shaped unit having a plurality of first outlet flow passages formed therein; and a second plate-shaped unit being stacked on the first plate-shaped unit and having a first inlet flow passage formed therein and a distribution flow passage formed therein, the distribution flow passage being configured to distribute refrigerant, which passes through the first inlet flow passage to flow into the second plate-shaped unit, to the plurality of first outlet flow passages to cause the refrigerant to flow out from the second plate-shaped unit, wherein the distribution flow passage comprises at least one branching flow passage, wherein the second plate-shaped unit comprises at least one plate-shaped member (23_1) having a groove formed as a flow passage, the groove having at least one branching portion for branching one branch part into two branch parts (23k, 23l), wherein the one branch part extends straight; characterised in that the two branch parts (23k, 231) extend straight in directions opposite to each other and perpendicular to a straight line part of the one branch part, wherein the at least one branching flow passage is formed by closing a region in the groove other than a refrigerant inflow region and a refrigerant outflow region, and wherein at least part of the refrigerant flowing into the at least one branching flow passage sequentially passes through the one branch part and branches at the two branch parts (23k, 23l) into one flow which passes through one of the two branch parts (23k, 23l) and an other flow which passes through the other of the two branch parts (23k, 23l), and wherein the one flow and the other flow each flow out into mutually different flow passages of the plurality of first outlet flow passages.