Devil rays (Mobula sp.) are in an endangered status, so conservation measures are needed. One of the first steps is to identify the level of genetic diversity. This study aims to determine the genetic diversity of mobula in Cilacap based on DNA bands of RAPD (Random Amplified Polymorphic DNA) polymorphism genetic markers. This research was conducted in September 2021 – June 2022. Sampling was carried out at PPS Cilacap and molecular analysis was carried out at the Biotechnology Laboratory building 3, Faculty of Fisheries and Marine Sciences, Padjadjaran University. The research procedure began with preservation of the devil rays (Mobula sp.) sample, isolation of sample DNA, electrophoresis of isolated DNA results, calculating DNA purity, DNA amplification, electrophoresis of DNA amplification results, and data processing and analysis. DNA isolation was carried out using the Promega Kit method. The electrophoretic results of DNA isolation from the three mobula rays samples showed quite good results. Band samples CIL 10 and CIL 9 looked thick and did not smear, while C13 produced bands and there was a visible smear. The results of calculating the purity of DNA isolated from mobula rays CIL 9, CIL 10, CIL 13 have a purity value of 1.94, 1.96, 1.80. Results The highest concentration of DNA was CIL-13 sample with a value of 452.90 ng/μL while the lowest concentration was CIL-10 which was 419.90 OPE-01 resulting in 10 out of 20 visualized polymorphic bands. The similarity index of CIL-9 to CIL-10 in the OPE-01 primer was 40% while the similarity index of CIL-9 and CIL 10 to CIL-13 was 35%. The average similarity index shows that the genetic diversity of the Mobula species is moderate. Morphologically, CIL-09 is a species of Mobula thrustoni, CIL 10 is a species of Mobula mobular, and CIL-13 is a species of Mobula tarapacana. CIL-9 (M. thrustoni) has a closer similarity index to CIL-10 (M. mobular) than CIL-13 (M. tarapacana). OPE-01 primer is good for analyzing diversity in mobula rays (Mobula sp.). OPE-01 has 10 out of 20 visualized polymorphic bands.