PURPOSE: To protect a window glass against an outside shock and to keep appearance in good condition by mounting the eaves on a bay window having a window frame and the window glass, and providing a shutter so that it can be wound by a winder incorporated into the outside eaves.

CONSTITUTION: The eaves 1 are constituted of an upper plate 11, a lower plate 12, a front plate 13 and side plates 14 and are mounted to an upper edge of an opening section k of an external wall K. After that, a window sill is constituted of an upper plate 21, a lower plate 22, a front plate 23 and side plates 24 and is mounted to the upper edge of the opening section K. Then, a bay window body 3 is constituted of a window frame 31, window glasses 32 and 32 and fittings 33a and 33b, it covers between the eaves 1 and the window sill 2, and the fittings 33a and 33b are constituted of jambs 331 and window glasses 332. After that, metal sutters 4a and 4b are provided to the outside of the bay window body 3 and are wound by a winder 5. The insulation is doubly made between the indoor and the outdoor by the window glasses 32 and 32 of the bay window body 3, the fittings 33a and 33b and the shutters 4a and 4b. According to the constitution, anticrime efficiency, fire resistance and heat insulation efficiency can be promoted.