BACKGROUND AND PURPOSE: Cerebral small vessel disease (CSVD) is a common subclinical feature of the aging brain. Steps per day may contribute to its prevention. We herein investigated the association between step counts and CSVD in a healthy Japanese male population. METHODS: We analyzed data from 680 men who were free of stroke and participated in this observational study. Seven-day step counts were assessed at baseline (2006-2008) using a pedometer. CSVD was assessed at follow-ups (2012-2015) based on deep and subcortical white matter hyperintensities (WMHs), periventricular hyperintensities, lacunar infarcts, and cerebral microbleeds on magnetic resonance imaging. Using a logistic regression analysis, we computed the adjusted odds ratios, with 95% CIs, of prevalent CSVD according to quartiles of step counts (reference: Q1). We also investigated the association between step counts and WMH volumes using a quantile regression. RESULTS: Steps per day were significantly associated with lower odds ratios, with the lowest at Q3 (8175-10 614 steps/day), of higher (versus low or no burden) deep and subcortical WMHs (odds ratio, 0.52 [95% CI, 0.30-0.89]), periventricular hyperintensities (0.50 [95% CI, 0.29-0.86]), and lacunar infarcts (0.52 [95% CI, 0.30-0.91]) compared with Q1 (≤6060 steps/day) but not cerebral microbleeds. An inverse linear association was observed between step counts and WMH volumes. These associations were independent of age and smoking and drinking status and remained consistent when adjusted for vascular risk factors. CONCLUSIONS: We found a J-shaped relationship between step counts and prevalent CSVD in healthy Japanese men, with the lowest risk being observed among participants with ≈8000 to 10 000 steps/day. Higher steps were also associated with lower WMH volumes.