PURPOSE: To accomplish compactification and to improve wind starting ability by curving blade parts so that the angle radius, which the curved face makes with a radius line employing the axial line as the center, in each part of the curved face of the blade parts is reduced as it goes toward the outside in the radial direction.

CONSTITUTION: In a fan shroud 7 for a heat exchanger, multiple blade parts 6, which are arranged at some intervals and are parallel to each other, are arranged in a rear part bell mouth 8, which is formed in the rear end part of a shroud main body 2 and is tapered toward the upstream side, while the curved faces of the blades 6 are parallel to the axial line of the shroud main body 2, and the curved faces are curved so that, in each part of the curved faces, an angle which the curved face makes with the radius line employing the axial line as the center is reduced as it goes further to the outside in the radial direction. Therefore, wind starting force in the vicinity of the tip part of blades 5 of a fan 4 is increased. Especially, a circumferential directional velocity component and a radius directional velocity component are large in the tip part of the blades 5 of the fan 4, so that air flow is smoothly faired by means of the blade parts 6 conforming with the flow in the flow direction, and the wind starting ability is improved as a whole.