A clamping device includes: an operating member; a wedge having a first inclined surface; a clamping member having a second inclined surface movable relative to the first inclined surface, the first and second inclined surfaces being provided in a face-to-face arrangement; and a housing having a first guiding part, a second guiding part and a chamber. The operating member is mounted in the first guiding part, the clamping member is mounted in the second guiding part, and the wedge is disposed in the chamber; the operating member is operated to move towards the wedge, such that the operating member contacts and pushes the wedge to move, and further the first inclined surface contacts and moves along the second inclined surface; whereby a pushing force of the operating member in a first direction is converted into a clamping force of the clamping member in a second direction.