There has been increased interest in sleep disorders in patients with inflammatory bowel disease (IBD). Studies in North America and Europe reported that the prevalence of restless legs syndrome (RLS) is much higher in patients with Crohn's disease (CD) than in the general population. The aim of this study was to reveal the prevalence and clinical features of RLS in Japanese patients with IBD and investigate the influence of RLS on sleep quality and quality of life (QOL). The study included 80 outpatients with IBD who visited Nagasaki University Hospital between December 2012 and July 2014. All patients completed the international RLS study group rating scale, a validated measure of the presence of RLS. Sleep quality was assessed using the Japanese version of the Pittsburgh Sleep Quality Index (PSQI), and health-related QOL was assessed using the Japanese version of the 36-item short form healthy profile (SF-36) version 2. The prevalence of RLS in patients with IBD was 20%, including rates of 21.7% in patients with ulcerative colitis (UC) and 17.6% in patients with CD. Among patients with CD, the proportion of women and serum level of CRP were higher in the RLS group than in the non-RLS group. Among those with UC, there were no differences in clinical characteristics between the RLS and non-RLS groups. Patients in the RLS group slept significantly less well than those in the non-RLS group (PSQI >5; 62.5 vs. 34.4%, P < 0.05). No significant relationships were observed between QOL indices and the presence of RLS (SF-36 physical score, 46.8 vs. 50.1; mental score, 43.8 vs. 45.7; role/social score, 48.1 vs. 49.2). RLS occurs frequently in Japanese patients with UC as well as CD. RLS affects sleep quality but not QOL, and it should be considered one of the causes of sleep disturbance in patients with IBD.