Proteus species infection is important cause of morbidity and mortality. This study was conducted to find out the prevalence and antimicrobial susceptibility pattern of Proteus species isolates at tertiary care university hospital in the central region of Japan from 2008 to 2010. Proteus species was identified by standard laboratory procedure. Antimicrobial susceptibility testing was performed by micro dilution assay according to CLSI recommendation. Of one hundred eighty-three Proteus species, one hundred thirty-nine Proteus mirabilis, and twenty-five Proteus vulgalis were isolated. About fifty-five Proteus species isolates were from outpatient. The major source of Proteus isolates were urine, pus, and sputum. Positive samples were received mostly from the urology and lowest from gastroenterology, ophthalmology and pediatrics. The effective antibiotics with over 95% susceptibility rates were amikacin, cefepime, and gentamicin. The numbers of extended-spectrum beta-lactamase (ESBL) producing isolates were twenty-nine and seven Proteus species isolates had ESBL-associated multidrug resistant ability. Proteus species infection spreads among community easily and inappropriate use of antibiotics contributes to their resistance. Continuous antimicrobial susceptible surveys are need for reducing the emergency of ESBL and multidrug resistance.