Recently, due to remarkable advancements in computer technology, small mobile computers such as PDAs (Personal Digital Assistants) and palmtop computers are being developed. In the near future, it is feasible that wearable computers will become commonplace. Up until now, some text input systems for wearable computers have been proposed. However, these systems, depending on the situation, have many problems like low speed input and restrictions on usage. In this paper, we propose a text input method for wearable computing environments utilizing two trackballs based on our previous proposal, entitled "DoubleMouse." This method supports the wearable property that it can be utilized anytime and anyplace. In addition, based on the movement direction of the two mice this method can rapidly select a user's desired input symbols into the computer, thusly mimicking a keyboard. Further, this method supports a "blind" input mode that allows input without displaying additional components on the screen. We also show how the developed system is useful in practical operations based on our experiments.