Background: The number of patients with dementia continues to increase as the age of aging continues to grow. Psychiatric symptoms caused by senile dementia are controlled using antipsychotics. However, these antipsychotics can lead to Parkinson's disease, and abuse of dopamine derivatives such as levodopa among Parkinsonian drugs can lead to psychosis. Therefore, we evaluated the patterns of prescribed antipsychotics and antiparkinsonian drugs in patients with senile dementia. Methods: We used data from the sample of elderly patients from the Health Insurance Review and Assessment Service (HIRA-APS-2016). We analyzed the patterns of prescribing antipsychotics and antiparkinsonian drugs including prescribed daily dosage, period of prescription, and number of patients with both antipsychotics and antiparkinsonian drugs for senile dementia. Results: Among the 159,391 patients with dementia included in this analysis, 4,963 patients (3.1%) and 16,499 patients (10.4%) were prescribed typical and atypical antipsychotic drugs, respectively. The most frequently prescribed typical antipsychotic was haloperidol (4,351 patients with dementia), whereas the atypical agent was quetiapine (12,719 patients). The most frequently prescribed antiparkinsonian drugs were in the order of levodopa/carbidopa, benztropine, and ropinirole. In addition, 1,103 and 3,508 patients prescribed typical and atypical antipsychotics, respectively, were co-prescribed antiparkinsonian drugs. Conclusions: Atypical antipsychotics were the preferred prescription in patients with senile dementia. The prescription dose was relatively low; however, the average treatment duration was mostly long-term. Selection of antipsychotics and/or antiparkinsonian drugs should be made carefully in senile dementia and the causal relationship of adverse drug reactions needs further study.