This study investigates the effect of periodic auditor designation on changes in rank-specific audit hours. Despite the increase in audit fees and audit hours caused by introducing the periodic auditor designation system, previous studies showed that there is no significant effect on the improvement of audit quality. This study confirms the effectiveness of the periodic auditor designation system, as verifying the change in audit hours for partner, senior and associate auditors, respectively. The results of the analysis which compares the changes of audit hours between designated and non-designated firms in 2020 are as follows. First, after implementing the periodic auditor designation, the increase of partner and senior auditor audit hours to designated firms was empirically greater than that of non-designated firms. Second, the auditor of designated firms showed an increase in senior-level audit hours under BIG4 auditor, while the increase in partner-level audit hours was mainly noticeable in small and medium-sized auditors. Finally, specialist auditors have shown a notable increase in senior auditor audit hours for designated firms, whereas for non-specialists, an increase in partners auditor audit hours is more pronounced.