The development of a scanning probe microscope (SPM) has provided us with atomic resolution images even without a special condition of vacuum. Its principle is that a probe tip traces on the sample surface to detect the information. Thus the property of the tip is directly reflected on the SPM images. Since a carbon nanotube was discovered, it has attracted attention as an ideal material for a SPM tip because of its unique structure and shape. In this article, we will describe the development and subjects to be overcome of a microscope, the potential of a nanotube for a SPM tip, how we have applied a nanotube to a SPM tip, and what we have imaged and done using nanotube tips.