An 80-year-old man was admitted to our hospital because of bradykinesia, muscle rigidity and respiratory dysfunction during sleep. Concerning bradykinesia and muscle rigidity, we diagnosed him as the early/moderate stage of Parkinson's disease without autonomic dysfunction. Polysomnography (PSG) showed a series of obstructive hypopneas and apneas. After administration of antiparkinsonian drugs, rigidity of the neck and trunk was diminished along with a drastic decrease in hypopnea on PSG. We consider that sleep hypopnea in this patient is caused by involvement of the striated musculature surrounding the upper-airway and/or rigidity in the trunk. These conditions are treatable with antiparkinsonian drugs.