The deteriorating cognitive functions experienced by cancer survivors subjectively have negative impacts on their daily lives, but they might not match the objective damage to their cognitive functions based on neuropsychological tests. The purpose of this study is to investigate the effects of mindfulness-based meditation training on the subjective and objective cognitive functions of cancer survivors. A group of cancer survivors participated in a two-hour group session once a week over eight weeks and practiced at home. All the participants were assessed for their objective and subjective cognitive functions before, after four weeks, and after the program. The analysis results show that their objective cognitive functions had significant improvement and their subjective cognitive functions maintained a baseline level, which indicates the program’s preventive effects. As for psychological and social variables, they decreased in perceived stress and increased in mindfulness with no changes to their happiness index. These findings raise a need to have different focuses of intervention that there is a need to take into further consideration their psychological aspects when cancer survivors complain about damage to their subjective functions with no impaired objective functions. The study discussed a need to test repeatedly based on a robust design.