Aripiprazole IM depot 400mg will be administered every four weeks for 20 weeks after drug switch / steady dose of oral aripiprazole tablets (each subject will receive 5 intramuscular injections totally).

administration of Aripiprazole IM Depot formulation at doses of 400 mg for 5 times in patients with schizophrenia.

To assess the Maximum Plasma Concentration (Cmax) of aripiprazole and its primary metabolite OPC-14857 after administration of the fifth IMD dose.

To assess the time of maximum observed plasma concentration (tmax) of aripiprazole and its primary metabolite OPC-14857 after administration of the fifth IMD dose.

To assess the time of maximum observed plasma concentration (tmax) of aripiprazole and its primary metabolite OPC-14857 after administration of the fifth IMD dose.

To assess the apparent clearance after extravascular administration (CL/F) of aripiprazole after administration of the fifth IMD dose.

Adverse events will be examined by frequency, severity, seriousness, discontinuation, and relationship to treatment

Mean change from baseline and the incidence of potentially clinically relevant abnormal values will be calculated for vital signs

To evaluate the change of Positive and Negative Symptoms Scale (PANSS) from baseline.