Elephant dung is rich in cellulose and lignin. Elephant dung has a color that varies from greenish to blackish, depending on the food consumed (Mathew & Mary, 2015). Meanwhile, elephant dung has not been used much. Therefore, elephant dung has not been fully utilized. elephant dung has not been fully utilized. Composting is an option to make elephant dung more useful. The purpose of this study was to determine the effect of the addition of EM-4 bioactivator on temperature, pH, moisture content, C / N ratio, organic matter produced and to determine the concentration of the EM-4 bioactivator solution which produces the best quality compost from elephant dung and in accordance with Indonesian National Standard (SNI) 19-7030-2004). This study used a completely randomized design (CRD). The treatment used 50 kg of elephant dung for one treatment and each concentration of EM-4 0 ml (control), 50 ml, 100 ml and 150 ml. The four treatments were repeated 2 times in order to obtain 8 experimental units. Observation parameters include compost temperature, pH, moisture content, organic matter, carbon, nitrogen, C / N ratio. The results of composting elephant dung with EM-4 solution for 2 months, it can be seen that the addition of EM-4 solution has an effect on temperature, water content, C / N ratio and organic matter while pH does not show a significant effect. In the treatment of adding 150 ml of EM-4 to 50 kg of elephant manure, the temperature reached thermophilic on day 28, namely 46.1 ͦC, C / N ratio 19.63 and 35% organic matter. All treatments comply with SNI 19-7030-2004.