Sandsjøen is a lake in Lierne municipality in Trøndelag county, Norway. It is located approximately 4 kilometers (2.5 mi) southeast of the municipal centre, Sandvika. The village of Holand is located on the north coast of Sandsjøen.
The lake, close to the Swedish border, is the beginning of the Sanddøla River, a major tributary of the Namsen River. The lake flows into Laksjøen lake in the west