Abstract. It is necessary to precisely measure pose (position and orientation) of a user in order to realize an augmented reality (AR) system with a wearable computer. One of major methods for measuring user’s pose in AR is visual marker-based approach which calculates them by recognizing markers pasted up on the ceilings or walls. The method needs 3D pose information of visual markers in advance. However, much cost is necessary to calibrate visual markers pasted up on the ceiling in a wide environment. In this paper, an initialization tool for installing visual markers in wearable AR is proposed. The administrator is assisted in installing visual markers in a wide environment by the proposed tool. The tool calibrates alignment of visual markers which exist in the real environment with high accuracy by recognizing them in the images captured by a high-resolution still camera. Additionally, the tool assists the administrator in repairing the incorrect pattern of marker using a wearabl...