A 16-years old man with severe ulcerative colitis (UC) was admitted to our hospital. After initiating treatment with corticosteroid for UC, chicken pox appeared. At the same time of appearance of chicken pox, the disease activity of UC was exacerbated. After initiating the treatment with acyclovir, both chicken pox and UC improved. Because colonoscopic findings revealed the remaining of moderately active UC, initiating the treatment with infliximab could induce clinical remission of UC without relapse of varicella-zoster virus (VZV) infection. This is a very rare case of UC with concomitant VZV infection. According to our report, the vaccination for VZV prior to immunosuppressive treatments would be necessary for VZV naïve patients with UC.