A gripper, being installed on a robotic arm, the robotic arm comprising a body and a tip axis, the tip axis including a flange face and at least one locking hole, the at least one locking hole being formed on the flange face, and a rotation central line being defined by the flange face, the gripper comprising: a housing, being fixed to the body and including a first guiding structure, the first guiding structure having a guiding rod extending along and coinciding with the rotation central line; a rotation element, being disposed in the housing, including a connecting surface being fixed to the flange face; a moving element, being movably disposed in the housing and connected to the rotation element, the moving element including at least one slot and a second guiding structure, the second guiding structure having a guiding hole extending along and coinciding with the rotation central line; and at least one claw body, being pivoted on the housing and partially extending into the at least one slot correspondingly; wherein the first guiding structure and the second guiding structure are assembled with each other, each of the guiding rod and the guiding hole has a non-circular cross-section corresponding to each other, and the moving element is constrained to move along the rotation central line so that the first guiding structure guides the moving element only process a linear motion along the rotation central line relative to the housing when the rotation element rotates along with the flange face; and wherein when the rotation element rotates along with the tip axis, the rotation element drives the moving element to process the linear motion along the rotation central line so that the at least one claw body pivotally rotates on the housing. a housing, being fixed to the body and including a first guiding structure, the first guiding structure having a guiding rod extending along and coinciding with the rotation central line; a rotation element, being disposed in the housing, including a connecting surface being fixed to the flange face; a moving element, being movably disposed in the housing and connected to the rotation element, the moving element including at least one slot and a second guiding structure, the second guiding structure having a guiding hole extending along and coinciding with the rotation central line; and at least one claw body, being pivoted on the housing and partially extending into the at least one slot correspondingly; wherein the first guiding structure and the second guiding structure are assembled with each other, each of the guiding rod and the guiding hole has a non-circular cross-section corresponding to each other, and the moving element is constrained to move along the rotation central line so that the first guiding structure guides the moving element only process a linear motion along the rotation central line relative to the housing when the rotation element rotates along with the flange face; and wherein when the rotation element rotates along with the tip axis, the rotation element drives the moving element to process the linear motion along the rotation central line so that the at least one claw body pivotally rotates on the housing.