The optical manipulation of biomacromolecules allows the study of the dynamics and interaction of molecules under mechanical tension. More importantly, the ability to manipulation single molecule at a time offers unique mechanical features of a specific molecule distinguishable to the ensemble study using the average over huge number of molecules. In this chapter, we introduce the basics of single molecule optical tweezers, the most successful examples of single molecule optical tweezers instrument, and the representative applications of the single molecule manipulation. This chapter will be reference for researchers who want to study the single molecule manipulation with optical tweezers. We also hope the chapter will excite more applications of the single molecule optical tweezers.