To provide a structure capable of discharging, as soon as possible, condensed water from the outermost fin on the lower side in a side-flow type parallel flow heat exchanger.

The heat exchanger 1 includes: two header pipes 2 and 3 arranged in parallel with a space; a plurality of flat tubes 4 arranged between the header pipes 2 and 3 and making a refrigerant path 5, which is provided therein, communicated with the inside of the header pipes 2 and 3; a plurality of fins 6 attached to the flat surfaces of the respective flat tubes 4; and side sheets 10U and 10D attached to the outsides of fins 6aU and 6aD located most outside among the plurality of fins 6. In the side sheet 10D located in the lower part of the heat exchanger 1, a plurality of notches 11 are formed, at spaces to each other, at the edge of the heat exchanger 1 on a side in which the condensed water concentrates. Each of the notches 11 has a width for covering space pitches P among the fins 6 by a plurality of pitches.