Recently, the increase in population of jellyfish is becoming a great menace to the oceans ecosystem, which leads to drastic damage to the fishery industries. To overcome this problem, a jellyfish removal system with trawl boats equipped with the jellyfish removal net has been suggested by NFRDI. However, the system needs large ships which need to be operated by a lot of human operators. Thus, this paper represents the design and implementation of an autonomous jellyfish removal robot system, called JEROS. The JEROS consists of an autonomous surface vehicle (ASV), a grid for jellyfish removal, and an autonomous navigation system. Once jellyfish are detected using a camera, the jellyfish removal scenario is started with generating efficient path to remove the jellyfish. Finally, the jellyfish is sliced up with the grid installed underneath the JEROS by following the generated path. The prototype of the system was implemented, and its feasibility was demonstrated through outdoor experiments and field tests.