With the growing number of ageing population in Sri Lanka and continuous expansion in the public sector employment tend to create dynamic consequences on the economy. While mandatory retirement age in the public sector is forcing the employees to quit from the job yet rising ageing population in the country is seeking for employment opportunities for retirees. Hence, the objective of this study is to find out factors affecting intended retirement age decision among the public sector employees in Sri Lanka. The theoretical lens used in the study is theory of planned behaviour. This is a quantitative study which applied stepwise regression and path analysis to examine the factors affecting intended retirement age. The sample was consisted of 400 staff grade public sector officials and conducted a survey through a self-administered questionnaire. The results indicated that perceived health and attitudes of the employees towards the retirement are the major factors influenced on intended retirement age decision among the public sector employees. Employees’ job satisfaction and family relationships have some impact whilst anticipated financial position has a minor impact on intended retirement age. The findings indicated the public sector organizations need to introduce health insurance schemes for employees and to maintain an attractive organizational environment and friendly organizational culture to inculcate positive attitudes towards working environment in order to delay the retirement of the employees.