Oral candidiasis is caused by Candida albicans. The symptoms including pain in the oral cavity affect our eating function. While some antifungal agents are commonly used for the treatment of candidiasis, occasional consumption of the effective dose cannot be tolerated due to side effects. There is also a possibility of induction of antifungal resistance, thus the development of replacement agents has been awaited. We aim to explore antimicrobial activities of essential oils. We evaluated the antifungal activities against C. albicans of essential oils from seven aromatic plants from three manufacturers, and of three chemotype essential oils from rosemary (Rosmarinus officinalis). As a result, we found that the antifungal activity was increased several times by the addition of Tween 80. All the tested essential oils showed stable antifungal activity, however, the variation was observed among the manufacturers of rosemary and eucalyptus. Rosemary has three chemotypes; CINEOL, CAMPHOR and VERBENON. They derived from a same plant species, but contain different chemical components. The CINEOL, dose-dependently decreased the number of C. albicans in the time-kill assay. Hence we concluded that the components of rosemary essential oil would have an effect on its antifungal activity. A chemotype is the first to consider in measuring antifungal activities of rosemary oil.