This study was designed to develop and validate a computerized exercise intervention program using the transtheoretical model (TTM) for Korean patients with type 2 diabetes mellitus (DM). This computerized program was web-based and developed by designing a flow chart. An expert group (n=24), who validated the content of the computerized program, produced a mean score for the evaluation scale of 4.25 (SD .56). Of the patients (n=28) with type 2 DM who participated in clinical validity testing of the program, the mean score for the satisfaction scale was 4.82 (SD .12). In the validation of the program, significant differences between baseline and after-intervention were observed in the stage of readiness for exercise (Z=-3.78, p < 0.001), physical activity (Z=-2.33, p < 0.05), blood glucose profiles [FBS (Z=-2.84, p < 0.01), pc 2hr. glucose (Z=-2.33, p < 0.05), HbA1c (Z=-2.77, p < 0.01) ], and VO2max (Z=-2.52, p < 0.01). The study confirmed that the computerized program could be used to construct a database and continue to provide follow-up intervention for patients in all stages.