Provided is a microneedle array which enables the quantitative and accurate insertion of a drug into the skin. It is found that, when a drug composition comprising a drug and an additive and having Vickers hardness of about 3 or more is applied to a microneedle array, the unintended removal of the drug can be avoided and the drug can be surely inserted into the skin along with the microneedle array. Consequently, the microneedle array coated with the drug composition according to the present invention can be used in the fields in which the drug is required to be administered with high quantitative performance even when the drug is contained at a low content, e.g., the administration of a vaccine, and the scope of application of the microneedle array can be extended.