Parkinson Disease (PD) is a neurodegenerative disorder of the central nervous system that often impairs the patient’s motor skills, speech and other functions. The four cardinal signs of parkinsonism are resting tremor, bradykinesia, cogwheel rigidity and postural instability. The prevalence of depression in PD ranges from 4% to 75%. However depression in PD is often mistakenly as the presentation of the disease itself. Therefore this paper reviewed the clinical feature of depression in PD and explored the aetiology of depression in PD.