To provide pliers capable of gripping and fastening a bolt and a nut, holding a pipe, and preventing a screw of a bolt from being crushed when gripping and fastening a bolt.

Recessed and curved parts 11 are provided to the insides of root parts of jaws 6 and 7 facing each other. Screw grooves 12 corresponding to a pitch of a screw S in respective fastened works W are formed in the horizontal directions of these recessed and curved parts 11. A curvature radius of the recessed and curved part 11 can be adjusted in accordance with the thickness of the fastened work W. The opening width of the opening portion 8 formed between the jaws 6 and 7 can be adjusted to several steps.