This study, based on a health belief model, examines how baby boomers perceive health and how they are financially preparing for future medical expenses. In addition, the study analyzes which factors influence baby boomers' preparation behaviors for future medical expenses and their perceived sufficiency of the preparation for medical expenses. Through such activities, this study examines baby boomers' current preparation status for future medical expenses, and based on this outcome, will turn the attention of individuals and society toward becoming more concerned with health and increasing health expectancy. For this study, an online survey was conducted targeted at men and women who were born between 1955 and 1963 and live nationwide, and its resultant data were collected. After conducting a 15-day survey in November 2011, a total of 418 questionnaire responses were used for the final analysis. The major findings of this study and their implications are as follows: First, baby boomers' health beliefs and their perceptions of health identified by subjective health conditions were very positive. Second, while there were some partial differences in the influencing factors, health beliefs and perceived health influenced the sufficiency of future medical expenses in the three groups, which were segmented according to how they prepare for future medical expenses-insurance-based, pension-based, and insufficiently prepared groups. Third, the baby boomers selected the national health insurance as the primary means of preparing for post-retirement medical expenses, and backed it up with private health insurance or the national pension. In addition, when baby boomers' perceived sufficiency of future medical expenses were examined, 57.6% of the respondents expressed that their old-age medical expenses were not sufficient. Fourth, in terms of baby boomers' preparation behaviors for future medical expenses, it was revealed that as one recognizes old-age health more seriously, he/she has a higher chance of using insurance and lower chance of using a pension to prepare for medical expenses. Fifth, regarding baby boomers' sufficiency of preparations for future medical expenses, economic factors such as total assets, the sufficiency of retirement assets, and the number of insurance policies, as well as health perceptions, including health beliefs and subjective health conditions, were important influencing factors.