A fuel directing reaction device for a passive fuel cell comprises: a substrate, which has a first side and a second side opposite to the first side; a fuel reservoir, which is disposed on the first side of the substrate; a fuel introducing microfluidic channel portion, which is disposed on the first side of the substrate and connected with the fuel reservoir; a first rib array portion, which is disposed on the first side of the substrate, and connected with the fuel introducing microfluidic channel portion; a second rib array portion, which is disposed on the first side of the substrate, and connected with the first rib array; and a plurality of reaction holes, each of which is disposed on the open side of the V-shaped portion of the second ribs and extends through the substrate to connect the first side and the second side of the substrate.