A microneedle includes a substrate having a first surface and a second surface which is a surface opposite from the first surface； a piercing projection projecting from the first surface of the substrate； and a group of surface-defining structures including three or more surface-defining structures, each of which has a surface-defining section. The surface-defining structure is either of a surface-defining projection which protrudes from the first surface and has a tip which serves as the surface-defining section and a surface-defining recess which is recessed from the first surface and has a bottom which serves as the surface-defining section. The surface-defining structure is located on an outer peripheral region of the substrate which is a portion surrounding the piercing projection as seen in a direction perpendicular to the first surface. A tip of the piercing projection extends beyond a plane which includes the surface-defining sections of any three of the surface-defining structures of the group of surface-defining structures.
