To provide a wind power generation device installable in an environment of urban buildings having relatively high density of population and articles, such as high-rise buildings or hotels, having specific safety and capable of effective power generation.

This device is provided with: a sealed wind power generation unit installed on the upper part of a building and having rotary vanes, a generator continued to the rotation shaft of the rotary vanes and displaced on the downstream side of the rotary vanes, and a casing for housing them; a negative pressure promoting means having one end connected to the exit on the downstream side of the sealed wind power generation unit; a wind guiding passage having one end connected to the upstream side of the sealed wind power generation unit and the other end disposed extensively to the side face or the lower part of the building; and an air introduction part formed in the wind guiding passage.