Technologies for the optical control of biomolecular functions have recently attracted considerable attention because they can be combined with advanced laser and microscopic techniques for diverse applications at the cellular and intravital levels. In this account, I review the summary of optical control technologies for biomolecular functions based on organic chemistry or protein science, and then introduce our recent studies on the development of small molecule-based photoregulation techniques. The first is the development of a photoactivatable protein labeling method based on a caged ligand. This method was applied to the photocontrol of intracellular protein dimerization and localization. The second is the development of a reversibly photoswitchable enzyme inhibitor, which was designed from the conformation of the inhibitor in the crystal structure of the enzyme-inhibitor complex. Based on our research strategies and results, I have also outlined the respective advantages and disadvantages of these two technologies: caged compounds and photoswitchable compounds.