A fuel cell gas supply and diffusion layer includes a sheet-like porous body layer, and a plurality of gas passage grooves formed on one surface of the porous body layer in parallel and formed in a zigzag shape or a wave shape respectively. As viewed in a plan view, a first rectangular region where circumscribes one gas passage groove and a second rectangular region where circumscribes a gas passage groove adjacent to the one gas passage groove overlap along a region in contact each other. An overlapping region where the first rectangular region and the second rectangular region overlap exists at any depth position of the grooves. According to the fuel cell gas supply and diffusion layer, it is possible to increase a power generation efficiency of a fuel cell.