This study considers effect of internal factors of working women on Impulse buying behaviour towards apparels in Batticaloa District, Sri Lanka. The data were collected from 230 working women in formal sector with a structured questionnaire. Data were evaluated with univariate and bivariate analysis to explore the levels of the variables, their relationship and their influences. Working women in formal sector expressed that their internal factors influence on the impulse buying behaviour. The factors considered in internal factors are shopping enjoyment tendency, Hedonism, Impulse Buying Tendency and Self-Identity. Correlation analysis discloses that the relation between internal factors and impulse buying behaviour is 44.2 at one percent significant level.