In recent years, floor-cleaning robots such as robot vacuum cleaners have been used in living spaces, and robots that can clean stairs have also been developed. On the other hand, most stair cleaning robots are limited to the treads. In this study, we propose a compact-sized stair-climbing robot that can clean not only treads but also risers. The stair-climbing small robot consists of leg wheels for stair climbing and a dual-arm manipulator for cleaning the treads and risers. The proposed configuration enables the robot to transform from a biped to a wheeled form, climb stairs based on the transformation, and wipe and clean the treads and risers through the coordinated use of the dual-armed manipulator and wheels equipped with cleaning sponges as end-effectors.