Mobile robots with omni-directional wheels can generate instant omni-directional motion including lateral motion without any extra space for changing the direction of the body. So, they are capable of traveling in every direction under any orientation to approach their destinations even in narrow aisles or tight areas. Especially, if a construction tool is combined to the mobile robot, it can be a mobile construction robot to be able to move from one position to another. In this research the Mecanum wheel, which is most frequently utilized in industrial fields, is selected to achieve omni-directionality of the mobile robot. Through intensive experiments, performance evaluation of the developed omni-directional mobile robot was conducted to confirm the feasibility for industrial purposes. Velocity performance and straightness for each directional motion were selected as performance indices to assess the omni-directional mobile robot. Ultrasonic sensors in-stalled on the frontal and lateral sides were employed to measure the real-time distance between the mobile robot and the side wall of workspace. The linear position, angular position and velocity of the mobile robot were calculated with the distance information.