In this study, the paddle for a swimmer with unilateral transradial deficiency to wear on the deficient side during training was designed. An experiment to acquire the swimming motions of a swimmer with unilateral transradial deficiency was conducted and the swimming motions without a paddle were analyzed using the swimming human simulation model SWUM. As a result, it was found that the contribution of the deficient limb to the thrust generation was only 16 % for the crawl and 12 % for the backstroke, respectively. Based on these results, the definition of appropriate load was newly proposed focusing on the increased rate in torque at the right and left shoulder joints. A parameter study to obtain the appropriate load was conducted with respect to the length and angle of the forearm part of the paddle, assuming the paddle size. The designed paddle will be produced and an experiment to evaluate it will be conducted in the near future.