The objective of the research was to study motivation factors effecting organizational engagement of physicians in Royal Thai Air Force. This study used mixed methods research that consisted of quantitative and qualitative research. The research instruments were questionnaire with the sample size was 202 physicians by convenience sampling and in-depth interview with 12 seniors and ex-Royal Thai Air Force physicians by purposive sampling. Data analysis by SPSS program. The statistics used in research were frequency, percentage, arithmetic mean, and standard deviation. T-test, One-Way ANOVA and Multiple linear regression analysis by using the enter methods were used to test hypothesis. The results were as follows 1) The motivation factors and organizational engagement of physicians in Royal Thai Air Force were at high level. 2) Royal Thai Air Force physicians who had difference gender, government income and education level had not difference organizational engagement. 3) Royal Thai Air Force physicians who had difference age, net income, work experiences and position level had difference organizational engagement. 4) The motivation factors that influenced organizational engagement in order of highest were policy and administration, responsibility, interpersonal relations, growth, security, recognition and welfare and compensation respectively. 5) Only interpersonal relations factor was negatively correlated with organizational engagement at statistic significant level of 0.05.