A 62-year-old woman developed B lymphoblastic leukemia (B-ALL) in April 2010, and achieved complete remission after hyper-CVAD/high-dose-MA therapy combined with rituximab. ALL recurred in December 2011, and remission was again achieved with the Japan Adult Leukemia Study Group (JALSG) ALL202 protocol combined with rituximab. Owing to a fever and rash that persisted from July 2012, the patient was examined again. On examination, redness was observed in the pharynx, and poorly defined oval erythemas were seen on the cheeks, posterior region of the neck, and upper arms. Blood test results showed high levels of ferritin, tumor necrosis factor (TNF)-α, an d C-reactive protein (CRP), and mild hepatosplenomegaly was identified on abdominal computed tomography (CT), indicative of an adult-onset Still's disease-like condition. Prednisolone therapy was initiated in August 2012, and remission was achieved. A second recurrence of ALL developed in September 2012, and although remission was again achieved using the JALSG ALL202 protocol, a third recurrence of ALL occurred in April 2013, and the patient could not be saved. In this case, adult-onset Still's disease-like erythema developed during the remission phase of ALL.