A microneedle including a substrate having a first surface and a second surface opposite to the first surface, at least one piercing projection projecting from the first surface of the substrate and being surrounded by an outer peripheral region of the substrate when viewed in a direction perpendicular to the first surface, and surface-defining structures positioned in the outer peripheral region and including three or more surface-defining structures each having a surface-defining section which is one of a surface-defining projection and a surface-defining recess. The surface-defining projection protrudes from the first surface and has a tip which serves as the surface-defining section, the surface-defining recess is recessed from the first surface and has a bottom serving as the surface-defining section, and the piercing projection has a tip that extends beyond a plane including the surface-defining sections of three surface-defining structures among the surface-defining structures.