The transdermal administration device of the present invention includes: a needle support with a plurality of microneedles formed at a tip portion thereof a holder with the needle support placed therein, allowing the needle support to protrude itself therefrom and retract therein and a cap for covering the microneedles, and further includes: a spring member placed between the needle support and the holder, for biasing the needle support in a protruding direction an engaging portion at a base of the needle support and an engaged portion capable of engaging the engaging portion, formed in the holder, where the engaging portion of the needle support can be locked with the engaged portion of the holder when the needle support is retracted in the holder.
