The paper investigates factors influencing the happiness of elderly migrants moving into urban areas, Northeast of Thailand. The research methodology was quantitative research. The unit of analysis was the individual level and the systematic sample were 276 elderly migrants moving into urban areas of Khon Kaen in 2013-2016. Data collection was done in April 2018 by the interview schedule that had both content validity and reliability at 0.912. Data Analysis employed by descriptive statistics and multiple regression analysis was implemented in multivariate analysis for hypothesis testing. The research results showed that most of the elderly migrants were female, 60-69 years, married and live together. Most of them finished primary school and more than half of the elderly migrants were employed after migration and had income less than 5,000 baht. Most of them had migration experience and got a moderate level of preparation themselves before migration. There were 3 of 4 elderly migrants had a high level of happiness. The finding also found that there were 6 factors that influenced the happiness of the elderly migrants with statistical significance at the level of 0.05, included income from careers, preparation before migration, previous migration experience, health care behavior, the role of the elderly in the household and participation in social activities. All variables could explain the variation of happiness among the elderly migrant by 46.3% (R2 = 0.463). Migration factors and the lifestyle factors were both the factors that affected the happiness of the elderly migrants and can encourage the elderly to get more happiness.