A layer-forming device that enables highly efficient layer formation and has a simplified configuration includes: a substrate feeding mechanism; a plasma-generating electrode; a space-partitioning wall; and a plurality of injectors. The plasma-generating electrode faces towards a feeding pathway of the substrate, and generates plasma using a reactive gas upon a supply of electric power. The space-partitioning wall is disposed between the feeding pathway and the plasma-generating electrode. A plurality of slit-shaped through-holes, through which radicals, ions generated from the plasma, or a portion of the plasma can pass, are formed at predetermined intervals in the space-partitioning wall. The plurality of injectors are sandwiched between the space-partitioning wall and the feeding pathway, such that each of the injectors is sandwiched between two adjacent through-holes from both sides of the two through-holes in the feeding direction, and the layer-forming gas is supplied toward the substrate through a layer-forming gas supply port.