PURPOSE: To clamp a tube with a different diameter by a scaffolding clamp that has simple structure and can be operated easily.

CONSTITUTION: A scaffolding clamp that is connected by orthogonally crossing two tubes with different diameters is composed of two tube-retaining parts 1a and 1b in nearly a U shape with a base part 3 and leg parts 4a and 4b. The tubes can be inserted into a fixed space that is surrounded by each base part and leg parts and is closed by a closing element 6 being hinge-locked to one end of at least one leg part, and the closed state can be retained by a wedge 7. Tube insertion openings 5 of each tube-retaining part orthogonally cross each other, the leg parts 4a and 4b of the U-shaped tube-retaining parts 1a and 1b are hinge-locked to base parts 3a and 3b, and the size of a tube-fixing space 2 is changed by a slot 9 of the closing element, thus clamping the tubes with different diameters.