The microneedle includes a base portion having a supporting surface and a protruding portion protruding from the supporting surface and having a through-hole penetrating the protruding portion along a direction in which the protruding portion extends. The protrusion has a flow path expanding portion configured to expand a communication path that connects the space in the through hole and the space surrounding the protrusion with an increase in the pressure of the fluid flowing through the through hole.マイクロニードルは、支持面を有する基体部と、支持面から突き出た突起部であって、当該突起部の延びる方向に沿って当該突起部を貫通する貫通孔を有する突起部とを備えている。突起部は、貫通孔内の空間と突起部を取り囲む空間とを連通させる連通路を、貫通孔を流れる流体の圧力の増加に伴って広げるように構成された流路拡張部を有する。
