Inclusion Criteria:  Idiopathic PD Hoehn and Yahr stage I to III Age 60~80 y/o Mini-Mental State Examination (MMSE) ≥24 Ability to ambulate independently (with or without walking aid)  Exclusion Criteria:  Affecting the peripheral vestibular system Medical condition that substantially influenced their gait and balance performance People had joined any rehabilitation past 1 month