A control device 1 of a cutting tool is revealed. For performing, cutting, opening and closing, the cutting tool includes a pair of handles 21, 22 pivotally connected to each other and each handle having a blade 211, 221. The control device is set on the handle 21 and involved in opening or closing of the blades of the cutting tool. The control device includes a first component 11 and a second component 12. The fist and the second components are connected to and locked with each other tightly by a fastening structure 113, 123. The control device is disposed on the handle closely, without loosening from the handle.
