Dysphagia is a potentially fatal symptom of Parkinson’s disease (PD) and is characterized by frequent silent aspiration, a risk factor for aspiration pneumonia. The transdermal dopamine agonist rotigotine alleviates dysphagia in patients with PD and is more effective than oral levodopa, suggesting the importance of continuous dopaminergic stimulation (CDS) in swallowing. Safinamide is a monoamine oxidase B (MAOB) inhibitor that facilitates CDS. In this retrospective open-label evaluator-blinded research, swallowing functions in nine patients with PD were examined using a video fluoroscopic swallowing study (VFSS) before and after treatment with 50 mg of oral safinamide. The VFSS results showed that safinamide significantly improved some swallowing measures during oral and pharyngeal phases, including oral transit time and pharyngeal transit time, without worsening of any measures. Notably, improvements in lip closure, an oral phase component, seemed to be most attributable to improvements in oral phase scores. In conclusion, a medicine for CDS may effectively improve swallowing functions in patients with PD. This is the first study to show that the MAOB inhibitor safinamide partly but significantly improves swallowing function in patients with PD.