The scanning tunneling microscope (STM) has recently appeared as a new instrument for surface science and has become a unique and important tool for material scinece. The tunneling effect, a well known quantum mechanical effect, is the basis of the new microscope. In the stage of its use, major purposes were to obtain atomic-scale images of conductive solid surfaces in vacuum. However, efforts have been made to observe the structure of organic materials even in the air at atmospheric pressure and in water. This may be of practical importance for many types of sample having biological interest. This short review is intended (1) to give a general overview of the principle and the current status of the STM and (2) to show its potential for the research of organic and biological materials with typical examples such as Langmuir-Blogedt films, adsorbed aromatic compound and deoxyribonucleic acid. Finally, a very preliminary result for an atomic handling of adsorbed molecule was given by using the STM as a high resolution probe.