A 24-year-old man was referred to our department for urinary retention and urinary tract infection. He was pointed out a bladder diverticulum in childhood. Computerized tomography (CT) scanning and magnetic resonance imaging (MRI) showed a bladder diverticulum, 10 by 8 cm in size, which was located posteriorly in the bladder. He underwent resection of the bladder diverticulum and left ureterovesiconeostomy. The histopathologic finding showed a bladder wall with thin muscular layer. The operation made urination possible with successful resolution of voiding symptoms. Herein we report this rare case of congenital bladder diverticulum which was treated in adulthood, and present a review the literature.