A heat exchanger bending method that performs bending by pressing a flat panel-like heat exchanger, in which heat transfer fins and heat transfer tubes are arranged with parts of the heat transfer fins projecting in a direction orthogonal to a lengthwise direction of the heat transfer tubes, against a bending die in such a way as to wrap the heat exchanger around the bending die, characterized in that: the heat exchanger bending method employs, as the bending die, a bending die having a curved surface whose bend radius changes in such a way as to become smaller from a starting point to an end point of the bending of the heat exchanger, the curved surface has a first curved surface, which is positioned near the starting point and has a bend radius that is large, and a main curved surface, which is positioned near the end point and has a bend radius that is smaller than that of the first curved surface, at the time of the start of the bending of the heat exchanger, the heat exchanger bending method performs a first step of bending the heat exchanger by pressing projecting sections of the heat transfer fins against the first curved surface in such a way as to wrap the projecting sections of the heat transfer fins around the first curved surface, and after the first step, the heat exchanger bending method performs a main step of bending the heat exchanger by pressing the projecting sections of the heat transfer fins against the main curved surface in such a way as to wrap the projecting sections of the heat transfer fins around the main curved surface, wherein the first curved surface is formed within the range of a wrap angle of up to 10 degrees from the starting point, and/or wherein the curved surface further has, between the first curved surface and the main curved surface, a second curved surface having a bend radius that is smaller than that of the first curved surface and larger than that of the main curved surface, and between the first step and the main step, the heat exchanger bending method performs a second step of bending the heat exchanger by pressing the projecting sections of the heat transfer fins against the second curved surface in such a way as to wrap the projecting sections of the heat transfer fins around the second curved surface, wherein the first curved surface and the second curved surface are formed within the range of a wrap angle of up to 20 degrees from the starting point. the heat exchanger bending method employs, as the bending die, a bending die having a curved surface whose bend radius changes in such a way as to become smaller from a starting point to an end point of the bending of the heat exchanger, the curved surface has a first curved surface, which is positioned near the starting point and has a bend radius that is large, and a main curved surface, which is positioned near the end point and has a bend radius that is smaller than that of the first curved surface, at the time of the start of the bending of the heat exchanger, the heat exchanger bending method performs a first step of bending the heat exchanger by pressing projecting sections of the heat transfer fins against the first curved surface in such a way as to wrap the projecting sections of the heat transfer fins around the first curved surface, and after the first step, the heat exchanger bending method performs a main step of bending the heat exchanger by pressing the projecting sections of the heat transfer fins against the main curved surface in such a way as to wrap the projecting sections of the heat transfer fins around the main curved surface, wherein the first curved surface is formed within the range of a wrap angle of up to 10 degrees from the starting point, and/or wherein the curved surface further has, between the first curved surface and the main curved surface, a second curved surface having a bend radius that is smaller than that of the first curved surface and larger than that of the main curved surface, and between the first step and the main step, the heat exchanger bending method performs a second step of bending the heat exchanger by pressing the projecting sections of the heat transfer fins against the second curved surface in such a way as to wrap the projecting sections of the heat transfer fins around the second curved surface, wherein the first curved surface and the second curved surface are formed within the range of a wrap angle of up to 20 degrees from the starting point.