Patent ID: 7090689

Claim:
A surgical instrument comprising: an insert section inserted into a patient's body; a tool section which is provided at a distal end of the insert section, which has first and second tool pieces connected to each other by a first opening/closing pivot pin and opened/closed by being turned relative to each other around the first opening/closing pivot pin, and which is capable of being articulated around at least one first articulating pivot pin orthogonal to a longitudinal center axis of the insert section; a manipulating section which is provided at a proximal end of the insert section, which has first and second manipulating bodies connected to each other by a second opening/closing pivot pin and opened/closed by being turned relative to each other around the second opening/closing pivot pin, and which is capable of being articulated around at least one second articulating pivot pin orthogonal to the longitudinal center axis of the insert section; an articulating link mechanism which connects the first manipulating body and the first tool piece to each other and causes the first tool piece to be articulated around the first articulating pivot pin due to articulating of the first manipulating body around the second articulating pivot pin; and an opening/closing link mechanism which connects the second manipulating body and the second tool piece to each other and causes the second tool piece to be turned around the first opening/closing pivot pin due to turning of the second manipulating body around the second opening/closing pivot pin, wherein the first opening/closing pivot pin is positioned at a first side relative to a longitudinal center axis of the insert section, the second opening/closing pivot pin is positioned at a second side relative to a longitudinal center axis of the insert section, and the first side and the second side form a substantially symmetrical position relationship to each other relative to the longitudinal center axis of the insert section, the articulating link mechanism and the opening/closing link mechanism comprising a total of at least three drive rods, and wherein a distance between a first pivot pin for turnably connecting the second manipulating body and the opening/closing link mechanism to each other and the second opening/closing pivot pin is defined to be equal to a distance between a second pivot pin for turnably connecting the second tool piece and the opening/closing link mechanism with each other and the first opening/closing pivot pin.