Surveillance is very important for preventing the nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA), and the pulsed-field gel electrophoresis (PFGE) method has long been used to identify the infection source and route as a molecular and epidemiological genotyping method. However, the use of the method in routine clinical laboratory measurements is difficult due to its complicated procedures. Since a molecular and epidemiological genotyping kit based on the POT (Phage Open-reading Frames Typing) method has been developed, we examined 192 MRSA isolates newly detected from inpatients in our hospital in 2010 in order to investigate the usefulness of POT for surveying outbreaks of MRSA. Among the 192 isolates 118 were suspected of nosocomial spread by the previous method, which defined a MRSA detection at more than 48 hours after admission as a nosocomial spread. The POT method was introduced at our laboratory in 2010, and we were able to recognize 38 patients as having strongly suspected nosocomial MRSA infection with the POT method taking into consideration the infection situation, such as places (wards and transfer) and time (date of admission and date of collected samples). Our Infection Control Division was confidently able to demonstrate the current condition of the nosocomial spread by providing the results to the clinical staff, who were also able to practice infection control confidently. We concluded that the POT method was very useful and convenient for investigating MRSA isolates and evaluating collected data because no particular analysis other than the digitizing electrophoretic pattern method was necessary.