It is an object of the present invention to provide a microbial fuel cell capable of increasing a current density without employing a mediator. The microbial fuel cell 1 includes a 3-dimensionally structured agglomerate formed from conductive fine particles 2 and microorganisms 3. In the agglomerate 4, the conductive fine particles 2 disperse among pieces of Shewanella 3 and the conductive fine particles 2 are coupled to one another to hold Shewanella 3, thus forming the 3-dimensional structure as a whole. Accordingly, with respect to Shewanella 3, conductive fine particles 2 hold Shewanella 3a on a surface of an electrode 103 and even Shewanella 3b positioned vertically away from the surface of the electrode 103. Hence, it becomes possible that more pieces of Shewanella 3 are allowed to transfer electrons.