The present invention aims to allow high molecular weight active ingredients to be contained in a coating agent substantially uniformly. For this purpose, a microneedle device 1 includes a microneedle base 2, and microneedles 3 capable of piercing a skin and being disposed on the microneedle base 2, wherein at least a part of a surface of the microneedles 3 and/or the microneedle base 2 is coated with a coating agent containing a high molecular weight active ingredient and a water-soluble polymer, and the content of the water-soluble polymer in the coating agent is 0.1 to 30% by weight, and the ratio of the content of the water-soluble polymer to the content of the high molecular weight active ingredient in the coating agent is 5:1 to 1:100.
