To provide a ventilation structure of a shed roof, which is improved in ventilation efficiency and water proofing properties.

The ventilator A forms a chevron shape in cross section corresponding to the ridge part of the shed roof, and is provided so as to cover a communication hole 47 formed at the ridge part, allowing the ventilation between an indoor side and an outdoor side. The slope portion 14 arranged on the roof surface side and a hanging portion 15 arranged on a wall surface side form the chevron shape in cross section, and both of the slope portion 14 and the hanging portion 15 include ventilation passages 38, 40 allowing the ventilation between the indoor side and outdoor side, and are formed asymmetrical relative to a virtual line dividing into two sections the apex angle of the chevron shape in cross section. Both of the slope portion and the hanging portion are provided with a ventilation port, causing a pressure difference hard to be generated between a small attic and the exterior of a roof.