A heat exchanger comprising: a plurality of refrigerant tubes through which a refrigerant flows, the plurality of refrigerant tubes extending in a horizontal direction; a heatsink fin in which the plurality of refrigerant tubes are inserted, the heatsink fin being configured to heat-exchange the refrigerant with a fluid; a head coupled to sides of the plurality of refrigerant tubes to extend in a vertical direction, the head being arranged to allow the refrigerant to be distributed into the plurality of refrigerant tubes, and the head comprising a head body defining a flow space of the refrigerant and a tube coupling part to cover a front side of the head body to be coupled to the refrigerant tubes; a partition part arranged to horizontally partition at least one space of an inner space of the head ; and at least two or more through holes , the at least two or more through holes guiding the refrigerant so that the refrigerant passes through the partition part to flow into the plurality of refrigerant tubes , the holes being vertically spaced apart from each other, characterized by further comprising a plurality of blocking ribs coupled to and below the partition part, the plurality of blocking ribs comprising a first blocking rib extending backward from a front surface of the head body and a second blocking rib extending forward from a rear surface of the head body, wherein the at least two or more through holes are defined in the rear part of the partition part , and wherein the partition part comprises a first partition part received within the head and a second partition part received within the first partition part , and the first and second partition parts comprise a pipe defining a refrigerant flow space, and wherein the first blocking rib is coupled to one side of the second partition part , and the second blocking rib is coupled to the other side of the second partition part . a plurality of refrigerant tubes through which a refrigerant flows, the plurality of refrigerant tubes extending in a horizontal direction; a heatsink fin in which the plurality of refrigerant tubes are inserted, the heatsink fin being configured to heat-exchange the refrigerant with a fluid; a head coupled to sides of the plurality of refrigerant tubes to extend in a vertical direction, the head being arranged to allow the refrigerant to be distributed into the plurality of refrigerant tubes, and the head comprising a head body defining a flow space of the refrigerant and a tube coupling part to cover a front side of the head body to be coupled to the refrigerant tubes; a partition part arranged to horizontally partition at least one space of an inner space of the head ; and at least two or more through holes , the at least two or more through holes guiding the refrigerant so that the refrigerant passes through the partition part to flow into the plurality of refrigerant tubes , the holes being vertically spaced apart from each other, characterized by further comprising a plurality of blocking ribs coupled to and below the partition part, the plurality of blocking ribs comprising a first blocking rib extending backward from a front surface of the head body and a second blocking rib extending forward from a rear surface of the head body, wherein the at least two or more through holes are defined in the rear part of the partition part , and wherein the partition part comprises a first partition part received within the head and a second partition part received within the first partition part , and the first and second partition parts comprise a pipe defining a refrigerant flow space, and wherein the first blocking rib is coupled to one side of the second partition part , and the second blocking rib is coupled to the other side of the second partition part . <EOS>