This cross-sectional study evaluated locus of control and its subscales in Parkinson’s disease. A total of 50 consecutive Parkinson’s disease participants and 50 healthy volunteers (control group) were enrolled. External locus of control was significantly higher in Parkinson’s disease participants, whereas internal locus of control had no significant differences. External locus of control and internal locus of control were correlated in control group, but not in Parkinson’s disease. In Parkinson’s disease participants, external locus of control was negatively associated with health-related quality of life as well as positively associated with emotional distress and disease severity (but not with disability). After adjusting to confound variables, the associations remained. On the other hand, internal locus of control was negatively associated with depression.