Users can set manually Android phone to do particular tasks on some situations. This type of setting is inconvenient, and also provide with unnecessary services, which don't consider users' situation. In this research, we design and implement a context-aware automatic task setting application. Users can get context-aware service by setting desired tasks based on contexts using this system. We design a language for describing context-action rules, and statically check validity of context-action rules by performing syntax and semantic check.■ keyword :|Context|Action|Context-Action Rule|Rule Checking|Task|Android|