The ice cream market in Indonesia was worth $575 eight million in 2021. The market is projected to grow at a CAGR of extra than 6% during the forecast duration. The study discussed an ice cream brand in Indonesia "No. I Japanese affordable ice cream in Indonesia" known as PT. XYZ. In the past two years, even though PT. XYZ succeeded in increasing their number of stores form 30% to 41%, however, at the same time the market share slightly decreased. The challenges had shown that PT. XYZ might have missed the opportunity in the moment of massive expansion. PT. XYZ must overcome the situation with the breakthrough marketing strategies. The store expansions all over Indonesia should take into account different preferences and diverse consumer's characteristics. In this study, Theory of reasoned action (TRA) and Theory of planned behavior (TPB) and consumer behavior basic model by Kotler & Amstrong (2019) are used, to examine the effect of external and internal stimuli to post purchase behavior.
Primary data collected through questionnaires distribution of 143 respondents in Greater Jakarta. The validity and reliability of the questionnaires were assessed using two statistical techniques which shows validity and reliability. The result of this research showed that all the variables (external stimuli, internal stimuli, impulse buying decisions) give positive effect to the post purchase behavior. After performing hypothesis testing, we know that the relationships between all variables have a positive effect and a significant relationship with each other.