To prevent a projecting part of a heat-transfer fin from being bent and broken in a bending work method for a heat exchanger to perform bending work in such a way that a plate-shaped heat exchanger, which is disposed so that a part of the heat-transfer fin is projected in a direction orthogonal to the longitudinal direction of a heat-transfer pipe, is pushed to a bender so as to be wrapped around the bender.

In the bending work method for an outdoor heat exchanger 7, the bender 55 having a curved surface 58, the bend radius of which changes so as to become smaller from the start point to the end point of the bending work for the outdoor heat exchanger 7, is employed. The curved surface 58 has a first curved surface 61 positioned near the start point and having a large bend radius and a main curved surface 62 positioned near the end point and having a bend radius smaller than that of the first curved surface 61. In this bending work method, at the start of the bending work, a first step is carried out in which the projecting portion of the heat-transfer fin 21 is pushed to the first curved surface 61. After the first step, a main step is carried out in which the projecting portion of the heat-transfer fin 21 is pushed to the main curved surface 62.