This study examines the effect of a voluntary auditor change on income smoothing. Investigating a sample of public companies for 2011-2018, we find that auditor changes are negatively associated with income smoothing when Big4 audit firms replace non-Big4 audit firms and that auditors consider previous earnings persistence. Overall, this study provides evidence that new auditors perceive income smoothing as opportunistic behavior, and this perspective is more prominent for Big4 audit firms. The results suggest that auditors, compared to investors and credit rating agencies, have a different perspective on income smoothing and auditors' evaluation depends on the earnings informativeness of client firms.