Recent years, shiitake cultivation using sawdust medium is increasing in Korea. The cultivation is performed in mainly greenhouses. One of major concerns in shiitake cultivation is the contamination of molds which cause damages and spoil the cultivation medium and/or inhibit the growth of shiitake mycelia in the medium. Although the harmful effects of molds are boradly recognized, there is no mush data on the source of molds contamination. This study was undertaken to check what fungi exist in indoor air of vinyl greenhouse used for shiitake cultivation. During last seven months period, we sampled air in two different vinyl greenhouses located in Cheongyang-gun, and Jangheung-gun, respectively. temperature and humidity average of a vinyl greenhouse located in Cheongyang-gun was 23.2℃ and 52.3% during spring season, and 26.3℃ and 79.1% during summer season. While, temperature and humidity average of vinyl a greenhouse located in Jangheung-gun was 21.4℃ and 61.7% during spring season and 32.8℃ and 70.9% during summer season. Seven mold species were isolated during spring season and six species during summer season from indoor air of the vinyl greenhouse located in Cheongyang-gun from season. In Janheung-gun greenhouse, seven species were isolated during spring season and four species during summer season. During the two investigated seasons, Trichoderma harzianum was dominant species in the two vinyl greenhouse air.