A heat exchanger, comprising a plurality of heat exchange members arranged side by side in a first direction so as to be spaced apart from each other, wherein each of the plurality of heat exchange members includes: a main body portion including a heat transfer pipe extending in a second direction intersecting with the first direction; and extending portions (8, 9) provided to the main body portion along the second direction, wherein the extending portions (8, 9) extend from ends of the main body portion in a third direction intersecting with both of the first direction and the second direction, and wherein, when a dimension of the main body portion in the third direction is represented by La [mm], a dimension of the extending portions (8, 9) in the third direction is represented by Lf [mm], a dimension of a wall thickness of each of the heat transfer pipes is represented by tp [mm], and a thickness dimension of each of the extending portions (8, 9) is represented by Tf [mm], relationship: Tf ≤ tp is satisfied; and wherein, when a dimension of each of the main body portions in a direction orthogonal to both of the second direction and the third direction is represented by Ta [mm] and each of arrangement pitches of the plurality of heat exchange members is represented by FP [mm], a relationship: Ta / Tf ≤ 5.6 × FP 1.3 is satisfied, characterised in that the main body portion includes an overlapping portion having a plate shape, which overlaps an outer peripheral surface of the heat transfer pipe, and overlapping portion is continuous with the extending portions (8,9), and wherein the extending portions (8,9) and the overlapping portion form a heat transfer plate, and the heat transfer plate is a member separate from the heat transfer pipe. wherein each of the plurality of heat exchange members includes: a main body portion including a heat transfer pipe extending in a second direction intersecting with the first direction; and extending portions (8, 9) provided to the main body portion along the second direction, a main body portion including a heat transfer pipe extending in a second direction intersecting with the first direction; and extending portions (8, 9) provided to the main body portion along the second direction, wherein the extending portions (8, 9) extend from ends of the main body portion in a third direction intersecting with both of the first direction and the second direction, and wherein, when a dimension of the main body portion in the third direction is represented by La [mm], a dimension of the extending portions (8, 9) in the third direction is represented by Lf [mm], a dimension of a wall thickness of each of the heat transfer pipes is represented by tp [mm], and a thickness dimension of each of the extending portions (8, 9) is represented by Tf [mm], relationship: Tf ≤ tp is satisfied; and wherein, when a dimension of each of the main body portions in a direction orthogonal to both of the second direction and the third direction is represented by Ta [mm] and each of arrangement pitches of the plurality of heat exchange members is represented by FP [mm], a relationship: Ta / Tf ≤ 5.6 × FP 1.3 is satisfied, characterised in that the main body portion includes an overlapping portion having a plate shape, which overlaps an outer peripheral surface of the heat transfer pipe, and overlapping portion is continuous with the extending portions (8,9), and wherein the extending portions (8,9) and the overlapping portion form a heat transfer plate, and the heat transfer plate is a member separate from the heat transfer pipe.