We propose a gait rehabilitation method using an elbow driving device. We focused on a coordinative relationship between upper limbs and lower limbs in walking, and the phase difference between the onset timing of elbow flexion and foot contact timing was controlled by the device. At first, we estimated an ordinary phase difference in young people whose right knee is fixed in extension, using motion capture system. Then we compared three settings of the desired phase difference: standard condition, right forward condition, and left forward condition. In the standard condition, the desired phase difference of both legs was set to the ordinary phase difference. In the right and left forward conditions, the desired phase difference of right and left legs were set to a smaller value than that of left and right leg, respectively. The result suggests that the patients with spastic gait improved on their gait stability and symmetry using rhythmic motor input.