This paper aimed to verify the effectiveness of the wearable robotic system "curara" for patients with spinocerebellar degeneration (SCD) by evaluating walking smoothness. The curara system supports the wearer's gait using a synchronization control method that uses a neural oscillator based on a central pattern generator network. The system reflects the motional intention by adjusting the synchronization gains. This modifies the degree of interactive coordinated motion between the curara and the wearer. As a feasibility study, we evaluated the waking smoothness of 10 patients with SCD using three gain condition settings. Harmonic ratio (HR), which has been used extensively to quantify the smoothness during walking, was used to assess their walking. The results show that most HRs in the medio-lateral, anterior-posterior, and vertical directions using the three gain conditions were higher than those for patients not wearing the system. In particular, the increasing rates of the HR in all directions during the gait support were 11.1%, 23.4%, and 23.2% compared with unassisted walking, when the gain condition settings of hip and knee joints are set at 0.4 and 0.5, respectively. Consequently, these results verified the effectiveness of the curara system for patients with SCD.