Recently we have shown that protein synthesis reactions can be light-triggered using a photoresponsive molecule (caged aa-tRNA). Brief exposure to light releases aa-tRNA, a key protein synthesis molecule, without damaging them, so that protein synthesis takes place at the time and location of irradiation. This method of spatiotemporally photocontrolling translation offers a promising approach for investigating the relationship between local translation and biological functions, such as embryonic development and cell differentiation.