Disclosed is a denture-fixing attachment freely adjustable in angle and position and including a rotation guide member installed at the center of the denture-fixing attachment, having a lower portion to be inserted into a fixture groove of a fixture, a thread being formed at a rim of the fixture groove, so that the rotation guide member may be coupled with the fixture having the fixture groove, a rotation guide member angle restriction cover positioned on the rotation guide member and provided therein with a through hole, and a ball joint having a ball joint lower portion placed in a rotation guide member inside provided in a ball joint angle restriction cover.