Pliers include a pair of handles, at least one arm member connected to one of the handles, a seat body secured in a receiving room of the arm member, a working jaw detachably engaged with the seat body, and a control assembly to control whether the working jaw is allowed to be released from the seat body. The working jaw defines in a side thereof an indentation to be communicated with a through hole of the seat body. The control assembly has a knob and a positioning pin. Rotation of the knob displaces the knob axially with respect to the seat body, causing the positioning pin to move between a locking position to stop the working jaw from departing from the seat body, and a releasing position where the working jaw is allowed to be removed from the seat body.