Recently, development in information technology is mainly focused on mobile service, and most of mobile users are using various services based on wireless network. So the importance of system software or middleware, which enables such mobile services, is growing bigger and bigger, and one of those is character input/output system. This paper will introduce an alphabet input system, which decomposes a character to a series of strokes, by its formation principal. It is designed to make a person, who knows the character, to input characters in the way that he/she is actually writing down the character.