A surgical instrument comprising: a first sheath having a distal end portion, a proximal end portion and a central axis extended from the distal end portion to the proximal end portion in a longitudinal direction; a pair of grip sections (101, 102) which are provided at the distal end portion of the first sheath and which are configured to relatively open and close; and a turning section which is connected between the first sheath and the grip sections, which is configured to turn an orientation of the grip sections in a direction deviating from the central axis of the first sheath; an opening-and-closing manipulating section which is provided at the proximal end portion of the first section and which is configured to open and close the grip sections; a turning manipulating section which is configured to turn the turning section; a heating member (124, 125) which is arranged in at least one of the grip sections and which is configured to generate heat by power supply, a second sheath inserted into the first sheath; an opening-and-closing drive shaft which is inserted into the second sheath, which is connected to the opening-and-closing manipulation section and which is configured to open and close the grip sections together with operation of the opening-and-closing manipulation section; and a turning drive shaft which is provided between the first sheath and the second sheath parallel with the longitudinal direction, which is connected to the turning manipulating section and which is configured to turn the turning section with respect to the longitudinal direction of the first sheath together with operation of the turning manipulation section. a first sheath having a distal end portion, a proximal end portion and a central axis extended from the distal end portion to the proximal end portion in a longitudinal direction; a pair of grip sections (101, 102) which are provided at the distal end portion of the first sheath and which are configured to relatively open and close; and a turning section which is connected between the first sheath and the grip sections, which is configured to turn an orientation of the grip sections in a direction deviating from the central axis of the first sheath; an opening-and-closing manipulating section which is provided at the proximal end portion of the first section and which is configured to open and close the grip sections; a turning manipulating section which is configured to turn the turning section; a heating member (124, 125) which is arranged in at least one of the grip sections and which is configured to generate heat by power supply, a second sheath inserted into the first sheath; an opening-and-closing drive shaft which is inserted into the second sheath, which is connected to the opening-and-closing manipulation section and which is configured to open and close the grip sections together with operation of the opening-and-closing manipulation section; and a turning drive shaft which is provided between the first sheath and the second sheath parallel with the longitudinal direction, which is connected to the turning manipulating section and which is configured to turn the turning section with respect to the longitudinal direction of the first sheath together with operation of the turning manipulation section.