There is provided a drug coating layer capable of preventing breakage of elongated drug crystals on a surface of the balloon and maintaining the drug crystals in an appropriate shape in order to act on the living body, and a method for forming the same. A drug coating layer (40) formed on a surface of a balloon (30), includes the plurality of elongated bodies (42) which are crystals of a water-insoluble drug and each have a long axis extending from the surface of the balloon (30) at various lengths and angles, and a water-soluble additive layer (41) which is provided in a space between an outer surface (51) of an aggregate (50) of the plurality of elongated bodies (42) and the surface of the balloon (30) so as to fill a space between the elongated bodies (42), the outer surface (51) being located outside the aggregate (50) and having an unevenness connecting a plurality of tip ends (46) and side surfaces (43) of the elongated bodies (42) to each other, in which the tip ends of the elongated bodies (42) hardly protrude from the additive layer (41), and the side surfaces (43) and/or tip surfaces (47) of the elongated body (42) are exposed on the surface of the additive layer (41).
