Ectopic extramammary Paget’s disease (EMPD) is a rare variant of EMPD that develops in non-apocrine regions. We present a 70-year-old man in whom ectopic EMPD affected the lower back. Initially, erythematous scaly plaques with several papules on the back were suggestive of Bowen’s disease. However, the biopsy specimen and immunohistochemical study results were consistent with EMPD features. The lesion was resected with a 1-cm safety margin and covered with a full thickness local skin graft. Ectopic EMPD is so rare that only few cases of EMPD in a non-apocrine region have been reported. We considered this case of EMPD on the back to be interesting since there has been no previous case reported in this location in Korea. (Korean J Dermatol 2018;56(6):380∼384)