Oil palm is a very important plant because it is one of the world's vegetable oil producing plants. Oryctes rhinoceros is one of the important pests that attack oil palm plants. The recommended control of Oryctes rhinoceros is used integrate pest control, one of which can use the biological agent of the fungus Metarhizium anisopliae. The composition of oil palm empty fruit bunches can be a medium rich in organic matter for the breeding of Fungus Metarhizium anisopliae. This research aims to study the best concentration of Metarhizium anisopliae in oil palm empty fruit bunch compost (metankos) to infect Oryctes rhinoceros larvae. This research was conducted in Laboratory of Plant Pests, Faculty of Agriculture, University of Riau, from April to October 2019. This study is experimental with Complete Randomized Design with 6 treatments and 5 replications. The treatment of Metarhizium anisopliae concentration on metankos consisted of : 0 g.l−1, 10 g.l−1, 20 g.l−1, 30 g.l−1, 40 g.l−1, and 50 g.l−1 Metarhizium anisopliae. The results show is concentration of Metarhizium anisopliae 50 g.l−1 water with a total mortality of 56% larvae.