Hypertrophic galls on Ipomoea triloba and I. lacunosa were found at Hiratsuka and Odawara cities in Kanagawa Prefecture respectively, in October and November 2005, 2006. The galls are produced on leaves, stems, petioles, buds, fruits and roots of the host plants and containing oospores. Usually, the white blisters (zoosporangial sori) are accompanied on the same hosts. Based on the optical microscopic observations, the fungus causing these gall formations was identified as Albugo ipomoeae-penduratae. This species was once reported 2000 in Japan, on cultivated Pharbitis nil, and its symptom is known as the "white rust of morning glory". Asexual and sexual morphologies are described and illustrated with time lapse micrographs of the process of zoospore formation and release.