Electric properties and current-induced structural changes of carbon nanotubes (CNTs) encapsulating copper nano-rods were studied by in-situ transmission electron microscopy (TEM). The diameter and the length of a copper filled CNT were 18 nm and 256 nm, respectively. The thickness of the graphite layer was about 1 nm. The bias voltage was applied between the two ends of the CNT inside the TEM, and the current as well as TEM images were recorded simultaneously. At a bias voltage of 1.4 V, the current increased to 10 microA, corresponding to a current density of 4.0 x 10(6) A/cm2, and at the same time the nano-rods inside the CNT started to move to an end of the CNT. After the movement of the nano-rods, an empty CNT was left. Resistivities of the CNT and the copper nano-rod were measured to be 3.0 x 10(-5) ohm m and 1.2 x 10(-4) ohm m, respectively.