A clamp unit is for interconnecting side wall beams of a concrete casting mold. The side wall beams incorporate protruding upper and lower edges. The clamp unit (1) includes at least two end portions (2,3) connected to each other and members (4,5,6) for adjusting the distance between the end portions. The end portions are advantageously connected to each other so that a spring-force is provided for moving the end portions farther or closer to each other.