Working memory (WM) is responsible for producing, maintaining, and manipulating cognitive representations of stimuli, searching for the same or similar stimuli in memory, and maintaining appropriate behavioral responses. WM is assumed to play a significant role in extant models of Attention Deficit Hyperactivity Disorder (ADHD). Using a single-case design with multiple baselines, we applied a computer-based cognitive rehabilitation program with adaptive training of WM tasks on 6 children with ADHD (inattention type) during 15 sessions – with each lasting 30 min– and evaluated the effects of the training. The obtained data were analyzed using visual analysis, percentage of recovery, and Reliable Change Index. The findings suggested that the program significantly enhanced the trainee’s performance in abilities pertaining to central executive functioning (CE), phonological loop (PH), and visuospatial sketchpad (VS) subsystems of WM. These results demonstrate that performance on WM tasks can be significantly improved by training, implying that that WM training has the potential to be of clinical use for ameliorating the symptoms of ADHD.