This study aimed to determined the right type and concentration of essential oils to inhibit microorganisms in the washing treatment on Java-apple fruit Dalhari variety. Research was conducted at the Post Harvest Laboratory of Muhammadiyah University of Yogyakarta from October to November 2018. The research method used was an experimental method arranged in a single-factor Complete Randomized Design (CRD) of various kinds of essential oils with 7 treatments. Observations made during the study were weight loss, texture, pH, total acid totalation, total dissolved solids and testing of Java-apple fruit microorganisms every three days for 15 days of storage. The results showed that the treatment of 0.1 % betel essential oil and lemon 0.8% is the best treatment in inhibiting the growth of microorganisms, preventing the increase in weight loss and maintaining hardness in Java-apple Dalhari variety.