In March of 2005, gray mold disease caused by Botrytis cinerea on Stachys sieboldii Miq. was occurred in the mud cellar storage of Gyeongsangnam-do Agricultural Research and Extension Services, Korea. The symptoms started with water-soaked and rotten in the tubers. The conidia were one celled and mostly ellipsoid or ovoid in shape and light gray in color. The conidia were 5~16 × 4~12 µm in size and the conidiophores were 14~30 µm in length. The pathogen formed conidia and sclerotia abundantly on PDA. The optimal temperature for mycelial growth and sclelotia formation was 20 oC. On the basis of symptom, mycological characteristics and pathogenicity test on host plants, the fungus was identified as Botrytis cinerea Persoon: Fries. This is the first report on gray mold of S. sieboldii caused by B. cinerea in Korea.