A microneedle unit includes a liquid holder, a microneedle, and a support member. The liquid holder has an enclosure that holds liquid including a substance to be administered. The microneedle has a base body and protrusions extending from the surface of the base body. The protrusions are of a hardness sufficient to pierce the liquid holder. The support member supports the base body in a state such that the microneedle is arranged at a position in which the tips of the protrusions and the enclosure holding the liquid are opposed to each other with a gap provided therebetween. The tips of the protrusions can be displaced to a position where the tips of the protrusions penetrate through the liquid holder in response to an external force applied to the base body.