According to one embodiment, a substrate processing device includes a stage configured to mount a substrate, a mold having a first surface facing an upper surface of an outer peripheral edge of the substrate and a second surface facing a side surface of an outer peripheral continuous with the upper surface of the outer peripheral edge, a mold moving mechanism configured to move the mold to bring the first surface close to the upper surface of the outer peripheral edge of the substrate and the second surface close to the side surface of the outer peripheral of the substrate, and a nozzle arranged in the mold, wherein the nozzle ejects resist.