The Carbon Nanotubes was reported which material showed hysteresis curve when it had been Nano-indentation test. To clarify the mechanism of this hysteresis, we prepared two different curvature radius diamond tips, and conducted Nano-indentation tests to CNT films. The AFM Nano-indentation realized penetration of diamond tip into CNT film, which means generation of friction force between diamond tip aspect and CNT tubes aspect. On the other hand, in the case of using sphere diamond tip, and cyclic Nano-indentation tests conducted same position, the load-displacement curve became similar to indentation test result of carbonaceous coating, it means that cyclic indentation for CNT made it like continues material. However, after several cyclic Nano-indentation tests to same position, the CNT specimen still showed hysteresis curve. These results indicated that hysteresis of CNT by Nano-indentation was related to friction between CNT tubes each other.