A grasping treatment unit includes a first jaw, and a second jaw openable and closable relative to the first jaw. In the first jaw, a heating wire continues without branching from a first extending end to a second extending end, and generates heat over an entire length from the first extending end to the second extending end when an electric current flows therethrough. A heating portion is lower in calorific value per unit area in a distal portion than in a proximal portion in the first jaw in a state where the heat is generated from the heating wire.
