Siek is an Amt ("collective municipality") in the district of Stormarn, in Schleswig-Holstein, Germany. The seat of the Amt is in Siek.

The Amt Siek consists of the following municipalities:

1. Braak
2. Brunsbek
3. Hoisdorf
4. Siek
5. Stapelfeld

53°37′34″N 10°17′53″E / 53.626°N 10.298°E / 53.626; 10.298