To provide an attic ventilation opening capable of inexpensively manufacturing with small-sized structure and facilitating execution by integrally forming a horizontal cylindrical body communicating with a vertical cylindrical body and opening upward of a tile upward of the vertical cylindrical body communicating an attic.

An attic ventilation opening 10 for integrally forming a lateral horizontal cylindrical body 12 providing an opening 15 upward of the tile of a ridge side communicating with a vertical cylindrical body is provided on the upper part of the vertical cylindrical body 11 communicating with an attic. A wire gauze 16 or a porous plate is preferably attached to the opening part 15 of the edge of the horizontal cylindrical body 12 of the attic ventilation opening 10. A cable insertion pipe 19 for the cable of an antenna and the electric cable of a solar heat panel is preferably provided on the inside of the horizontal cylindrical body 12. Thereby the attic ventilation opening 10 capable of inexpensively manufacturing a small-sized structure and facilitating execution can be obtained.