Objective This study investigated the effects of process-based cognitive training that targets working memory and cognitive control on memory improvement in healthy elderly individuals and patients with mild cognitive impairment (MCI). Methods Forty healthy subjects and 40 patients with MCI were randomly assigned to either the intervention or control group. The intervention group received 12 sessions of designated cognitive training. The control group did not receive cognitive training. A memory test was administered pre-intervention, post-intervention, and 4 weeks after the intervention. Additional comprehensive neuropsychological tests were also administered including a depression scale questionnaire. Results Performance in attention and working memory, which are directly related to the training domains, and global cognitive function were improved in the intervention group after training. In memory tests, interference by irrelevant stimuli was reduced and recognition memory was improved after the intervention. Furthermore, cognitive training ameliorated depressive symptoms. These training effects were not dependent on MCI status. Conclusion Process-based cognitive training that targets working memory and cognitive control effectively improves memory processes including retrograde interference and recognition, as well as depressive symptoms associated with aging in healthy elderly individuals and patients with MCI. Psychiatry Investig 2020;17(8):751-761