The purpose of this study was to discuss the effect of a Robotic Knee Orthosis exercise using an ABA-type single case study. The subjects were 5 hemiplegic stroke patients in a recovery rehabilitation unit. The Berg Balance Scale, stride length, step length, the of one-leg support time and the 10-meter gait time improved in phase B. Author:S.Iida, T.Watanabe, D.Kawakita.