To enable a suction cup to be installed on a surface not slippery therefor by assigning the suction cup to include a flat and smooth surface on its obverse side and a means for fixing the adapter plate on its reverse side.

An adapter plate includes an obverse side 1 and a reverse side 2. On the reverse side 2, a fixing means composed as an adhesive thin film 3 is attached. The adapter plate is constructed as a circular disc. An annular projection edge 4 is formed on the outer circumference of the adapter plate. The projection edge 4 extends from the obverse side 1 in a direction opposite to the reverse side 2. A recess is formed owing to the projection edge 4 and a suction cup 5 displayed above the adapter plate can be exactly set in this recess. It is blocked to make approach sideways in a range between the suction cup 5 and obverse side 1 of the adapter plate. Since the suction cup 5 is surrounded by the projection edge 4, the absorptive force of the suction cup 5 increases.