Paliperidone is an atypical antipsychotic derived from 9-hydroxyrisperidone. Paliperidone shows antagonistic activity on dopamine D2, serotonin 5HT2A, and histamine H1 receptors as well as the alpha1 and alpha2 adrenergic receptors. Paliperidone palmitate is an injectable form of paliperidone that has long-lasting potency and has been developed to improve treatment compliance in patients who have schizophrenia. Paliperidone shows high binding affinity to dopamine D2 and serotonin 5HT2A receptors. It also shows significant binding affinity to α_2a receptors. This leads to an increase in serotonin release, which may also induce antidepressant activity. Although it seems to be paradoxical, manias that are associated with atypical antipsychotic drugs have been reported in the literature. However, very little research has been published on paliperidone- and paliperidone palmitate-induced mania. This report will discuss the case of a patient who was hospitalized with a diagnosis of schizophrenia and manic symptoms during paliperidone palmitate treatment.