Restrictions on the use of antimicrobial agents are reported to lead to a reduction in the use of carbepanem (CP) antiobiotics and in the detection of resistant bacteria. Our hospital began monitoring the use of specific antimicrobial agents in June 2014. In the present study, we examined changes in the use of injectable broad-spectum antibiotics and in the susceptibility of Pseudomonas aeruginosa before and after introducing our antimicrobial use monitoring system (pre-and post-monitoring). We obtained a total of 301 specimens taken before the introduction of the system (January 2012-May 2014,143 specimens) and after after the introduction (June 2014-December 2016, 158 specimens). We then examined antimicrobial use density (AUD) and P. aeruginosa sensitivity per 100 patient-days.Comparisons of pre-monitoring results (2012) and post-monitoring results (2016) show that AUD decreased for imipenem/cilastatin (IPM/CS;0.26 to 0.1), meropenem (0.46 to 0.19), CAZ(0.52 to 0.16), and CZOP (0.17 to 0.09) and increased for tazobactam/piperacillin (0.67 to 1.16). Susceptibility of P. aeruginosa tended toward recovery (IPM/CS:0.8 to 0.87, piperacillin: 0.89 to 0.92, ceftazidime: 0.87 to 0.93,and cefozopran: 0.8 to 0.94). Our antimicrobial use monitoring system reduced the use of CP antibiotics and helped to restore the susceptibility of P. aeruginosa.