Parkinson's disease (PD) is a slowly progressive disorder which begins with motor symptoms. Several cognitive deficits can be observed in nondemented patients with PD during their history. The core symptom in the cognitive deficits in PD is the executive dysfunction. Neuropsychological tests such as Wisconsin Card Sorting Test, Trail Making Test are used to measure the degree of this dysfunction. Executive dysfunction is thought related to abnormalities in the dorsolateral prefrontal circuit which largely passes through the caudate nucleus. The dysfunction emerges as the pathology spreads to the nigrocaudate project corresponding to Hoehn & Yahr stage II-III. Effective therapy for cognitive dysfunction in PD remains elusive, however donepezil, Attention Process Training, Music therapy and Transcranial magnetic stimulation have been reported to have partial efficacy.