Complex sphingolipids and sterols are coordinately involved in various cellular functions, e.g. the formation of lipid microdomains. Here we found that budding yeast exhibits resistance to an antifungal drug, aureobasidin A (AbA), an inhibitor of Aur1 catalyzing the synthesis of inositolphosphorylceramide, under impaired biosynthesis of ergosterol, which includes deletion ofERG6,ERG2,orERG5involved in the final stages of the ergosterol biosynthesis pathway or miconazole; however, these defects of ergosterol biosynthesis did not confer resistance against repression of expression ofAUR1by a tetracycline-regulatable promoter. The deletion ofERG6, which confers strong resistance to AbA, results in suppression of a reduction in complex sphingolipids and accumulation of ceramides on AbA treatment, indicating that the deletion reduces the effectiveness of AbA against in vivo Aur1 activity. Previously, we reported that a similar effect to AbA sensitivity was observed whenPDR16orPDR17was overexpressed. It was found that the effect of the impaired biosynthesis of ergosterol on the AbA sensitivity is completely abolished on deletion ofPDR16. In addition, an increase in the expression level of Pdr16 was observed on the deletion ofERG6. These results suggested that abnormal ergosterol biosynthesis confers resistance to AbA in aPDR16-dependent manner, implying a novel functional relationship between complex sphingolipids and ergosterol.