The purpose of this study is to determine whether levodopa/benserazide dispersible is effective in the adjunctive treatment of Parkinson's disease (PD) patients with delayed ON.

Delayed ON is one of the motor complications of advanced PD patients that effect of anti-parkinsonian medication is delayed more than 40 minutes after intake. In the most severe cases, the effect does not appear even until next medication schedule, so called "No ON" status. It is important to manage delayed ON properly because it can interfere motor functions and quality of life of PD patients.

Levodopa/benserazide dispersible can be absorbed rapidly in the intestine, so theoretically it can break the poor response to conventional treatment of PD patients with delayed ON. However, this has not been proven by clinical trials till now.

Inclusion Criteria:

• Male or female patients between 31 and 80 years
• Parkinson disease (PD) was diagnosed by United Kingdom Parkinson disease brain bank criteria
• Patients receiving stable Levodopa treatment at least 2 weeks prior to baseline visit
• Delayed ON was confirmed by a specialized PD diary that records change in motor symptoms 90 minute after the first morning dose. Delayed ON is defined as delay of more than 40 minutes after the first morning dose for resolution of OFF state or experience of no ON state at least 1 per week.

Exclusion Criteria:

• Existence of cognitive decline hard to participate in the clinical trial or K-Minimental Status Exam score 24 or less
• Any contraindication of blood sampling
• Subjects with clinically significant psychiatric illness
• Subjects with a cancer or severe medical illness
• Lactating, pregnant, or possible pregnant
• History of malignant melanoma
• Subjects with narrow-angle glaucoma
• Subjects with hypersensitivity to levodopa or benserazide
• Subjects treated with non-selective monoamine oxidase (MAO)-B inhibitors
• Subjects with peptic ulcer, colitis, or gastrointestinal disease