To provide an uneven space formation preventing compression type holding clamp which has a simple structure, has water-tightness, and achieves excellent workability.

An uneven space formation preventing compression type holding clamp includes: an aluminum clamp 10 including an insertion hole 12 into which a steel core aluminum twisted wire is inserted; a steel clamp 30 which has a core part steel wire insertion hole 33, in which a core part steel wire of the steel core aluminum twisted wire penetrating through the insertion hole 12 is inserted and compressed, at one end and a holding hole 34, which is held to a steel tower, at the other end; and an aluminum pin 20 inserted into the aluminum clamp 10. The steel clamp 30 has a plane part 35 contacting with the aluminum pin 20, and the aluminum clamp 10 has a pin insertion hole 15 into which the aluminum pin 20 is inserted.