We have attempted to observe straining responses of an individual multi-walled carbon nanotube (MWNT) by performing an in-situ tensile testing inside scanning electron microscope (SEM). The both ends of an individual MWNT was attached on the rigid support and the tip of the force sensor using electron beam and was elongated by a nano-manipulator. The nano-manipulator was automatically controlled by personal computer. Linear deformation and fracture behaviors of MWNT were successfully observed and its force-displacement curve was also measured from the bending stiffness and displacement of the force sensor and manipulator. The tensile properties of individual MWNT were evaluated from the tensile test results.