Household air conditioners are known to be contaminated with dematiaceous fungi such as genus Toxicocladosporium and genus Cladosporium. We frequently encounter cases in which a large amount of fungi, which are presumed to belong to the family Cordycipitaceae, are isolated from the blowout air of the household air conditioners. Therefore, the Cordycipitaceae isolated in the survey of four cases of the air conditioners were identified by genetic analyses. As a result, all of them were found to be Simplicillium sympodiophorum. The concentration of airborne fungi, S. sympodiophorum in the blowout air was high (> 10⁴ cfu/m³) as exceeding the upper limit of quantification in three of four cases, and 5,000 cfu/m³ in one case. This study revealed that S. sympodiophorum contaminated multiple air conditioners. Genus Toxicocladosporium was also isolated from the two air conditioners, and it was found to be Toxicocladosporium irritans by the genetic analysis.