The objective of this study is to investigate an effect on the antimicrobial appropriate use of the antimicrobial stewardship. We investigated the consumption of injectable antimicrobials from 2001 to 2007 and the administration period of specific antimicrobials (carbapenems, fourth-generation cephalosporins, anti-methicillin-resistant Staphylococcus aureus (MRSA) agents) in the individual patient. Since September 2004, the infection control team at Osaka University Hospital has been promoting appropriate use of antimicrobials through consultation, education, and weekly surveillance of specific antimicrobial usage. We obtained the amount of all antimicrobial injections as titer from the medical information database of the electronic medical chart system retrospectively. Antimicrobial use densities (AUD) were evaluated by measuring the number of doses administered/1000 patient-days. Although the number of inpatient admissions and operations increased 1.53- and 1.39-fold, respectively, in the seven years from 2001 to 2007, the expenditure on specific antimicrobials decreased markedly with AUD of specific antimicrobials decreasing from 39.6 to 29.2. The percentage of inpatients receiving specific antimicrobials decreased from 19.8% to 9.8%, and the ratio of the number of inpatients administered a specific antimicrobial within seven days to the number of inpatients administered each specific antimicrobial increased to over 60%. This led to reduction in the total expenditure of antimicrobials by about \\100 million annually. The incidence of hospital-associated MRSA (HA-MRSA) infection decreased from 0.93% (2003) to 0.68% (2007). We can reduce the expenditure of antimicrobials without increasing incidence of the HA-MRSA by antimicrobial stewardship, and we think that appropriate use of antimicrobials is achieved progressively.