A pliers has guiding surfaces at tooth portions of the first pliers body and tooth portions of the engaging unit of the control member. Therefore, when the pressing block of the control member is not pressed, even if the first pliers body is engaged with the tooth portions of the engaging unit, the second pliers body can still be pushed forward relative to the first pliers body, so that the second guiding surfaces of the second tooth portions of the engaging unit slide relative to the first guiding surfaces of the first tooth portions and each of the first tooth portions is moved to engage with a next corresponding second tooth portion, thereby allowing the second pliers portion being movable toward the first pliers portion. Hence, the clamping distance of the pliers can be adjusted to match with an object to be clamped.