To solve the following problems: conventional eaves is three-dimensionally assembled to secure strength, which makes the eaves itself heavy, and therefore has to be firm in order to be supported; and thin eaves of the previous invention are hard to attach, although suffering little damage by virtue of the lightness of the thin eaves when broken by a typhoon etc., and having a similar effect to the one added with a reinforcing effect because they are attached in an arch shape.

A lower cut portion (5) of an attachment surface (1) is formed in a convex shape and straightly attached, so that a top surface of the eaves (4) are spontaneously formed in the arch shape. In this method of attaching the eaves, two fixing holes (2) opened in the center of the attachment surface (1) are attached along a window frame (11) by means of a screw nail etc. Subsequently, residual-stress holes (3) opened at both ends are attached along the window frame (11). After that, by attaching the residual-stress hole (3) between them, the top surface (4) of the eaves is spontaneously formed in the convex arch shape.