The present invention provides a transdermal drug delivering device which solves the problems that in the prior art, because absorptive force of an outer annular cavity caused by negative pressure is weakened, an application disk is prone to falling off. The transdermal drug delivering device comprises a first top, an annular outer wall, an annular inner wall, a first connecting tube and a middle annular cavity, wherein the annular outer wall and the annular inner wall are arranged on the two sides of the first top and fixedly connected with one side face of the first top, the first top, the annular outer wall and the annular inner wall constitute a first annular cavity, one end of the first connecting tube is communicated with the first annular cavity, the other end of the first connecting tube is communicated with a negative pressure source, the central annular cavity is used for placing drug and comprises a first annular wall and a second top face, the first annular wall is connected with one end of the annular inner wall through an annular bottom face, and the annular inner wall, the annular bottom face and the first annular wall form an annular groove with the opening in the direction of the first top. The transdermal drug delivering device adapts to changing of curvature through the opening and the closing of the upper end of the annular groove, and therefore the first annular cavity is prevented from being controlled by the second top face, and the application disk applied on the portion out of flatness is not prone to falling off.
