Executive function is a very high-dimensional function that monitors, regulates, and maintains an individual’s behavior, cognition, and emotion. Moreover, it is necessary for individuals’ optimal adjustment. According to recent research, executive function affects children’s and adolescents’ adjustment so that their attention, learning, behavioral problems depend on their executive function. Without appropriate executive function, children and adolescents have reported adjusting less effectively. The good executive function seems to work as a protective factor for various problems that are considered to be onset during childhood or adolescence. Specifically, as brain imaging skills have been developed, it has been found that executive function has an important role in very young children. Therefore, many clinicians or researchers should pay attention to the executive function of children and adolescents. In the current study, we reviewed general features of executive function, specific characteristics of executive function during childhood or adolescence, the relationships between executive function and intelligence or psychopathologies. Moreover, we overviewed the tools for measuring or assessing the executive function of children or adolescents. Lastly, we introduced the interventions for improving executive function.