Patent ID: 8439826

Claim:
A medical instrument comprising: an operation portion provided with a movement sensor and a switch; an insertion body to be inserted into an interior of an object to be examined, the insertion body being connected to the operation portion; a distortion detection unit disposed in the insertion body in which a plurality of distortion detection sections for detecting distortion of the insertion body are formed; a coordinate calculation unit that calculates first coordinates of the respective distortion detection sections using any one of the plurality of distortion detection sections as a reference point in a first coordinate system defined by a correlation between the reference point and the distortion detection sections; a reference coordinate system setting unit that sets a second coordinate system having a reference point and axial direction based on a position and an orientation of the movement sensor when the switch is pressed; a coordinate transformation unit that transforms the first three-dimensional coordinates of the respective distortion detection sections to second three-dimensional coordinates in the second coordinate system set by the coordinate system setting unit based on a relative positional relationship between the reference point set by the reference coordinate system setting unit and the reference point set by the first coordinate system; and a display unit that displays a shape of the insertion body based on the second coordinates transformed by the coordinate transformation unit.