A drug coating layer which ensures that when a medical device coated with a drug is delivered into a living body, the drug can be prevented from peeling off during delivery operation through a body lumen or cavity such as a blood vessel； and/or a drug coating layer excellent in transferability of a drug to a target tissue； and a method of controlling the morphological form of a drug coating layer are provided. The drug coating layer, which is formed on a substrate surface and contains a water-insoluble drug, has at least one morphological form selected from the group consisting of defined morphological forms (1) to (4)
