This study describes a long-sleeved shirt dressing support system, which mainly comprises two robotic manipulators, for people with half-body paralysis. To design a feasible support system, we obtain the opinions of occupational therapists and experimental psychologists. Based on their advices, we propose herein an appropriate dressing procedure that can be supported by robots. We also construct a robotic system to achieve the required assistance and implement some essential functions, including human pose recognition, end-effector trajectory generation for shirt sleeve manipulation, and arm motion support while dressing. Accordingly, we introduce admittance control for the arm motion support. This avoids the trouble of a person getting a large load while putting his/her arm through a shirt sleeve. We present the experimental results of an actual person wearing a long-sleeved shirt to show the usefulness of the proposed system.