Provided is a floating-type microbial fuel cell capable of effectively generating energy from organic contaminants of contaminated waters. The floating-type microbial fuel cell includes a cathode, an anode electrically connected to the cathode, and a floating unit connected to the cathode and/or the anode and floatable in a substrate solution, wherein the cathode is positioned at a region in the substrate solution having a dissolved oxygen concentration higher than that of a region at which the anode is positioned, and the anode is positioned at a region in the substrate solution having an amount of electrons generated by microorganisms larger than that of a region at which the cathode is positioned.