The powdery mildew of safflower (Carthamus tinctorius L.) extensively occurred at 1999 at the experimental farm of Kyongsangnam-do Agricultural Research and Extension Services. Both sides of the leaves and the older stems were covered with the fungus, and then the leaves and stems turned yellow. The conidia, conidiophores and perithecia were observed on the leaf lesion. Perithecia were ellipsoidal, $80-117;{mu}m$ in diameter. Asci were subglobose and $84{sim}99{ imes}59{sim}73;{mu}m$ in size. Ascospore were ellipsoidal to ovoid, and $15{sim}34{ imes}11{sim}23;{mu}m$ in size. Conidia were ellipsoid to barrel-shaped, $25{sim}37{ imes}11{sim}22;{mu}m$ in size and formed in long chains. The causal organism was identified as Sphaerotheca fuliginea. This is the first report on powdery mildew of safflower caused by Sphaerotheca fuliginea in Korea.