Mekar Swalayan is one of the businesses owned by Kopkar PT. Gudang
Garam Tbk. Kediri is aimed at improving the welfare of its members, and along with the development of the retail industry in Indonesia which is closely related to daily life in modern society. This research was carried out with the aim of finding out, explaining and proving the hypothesis that store atmosphere, product differentiation and service quality influence product purchasing decisions at Mekar Swalayan. The quantitative research method of causal associations was used in this research, where the sampling method was accidental sampling using a questionnaire and Likert scale. Where the population of this study is all Mekar Swalayan consumers whose number is unknown. The sample for this research consisted of 384 respondents using the Lemeshow formula, the terms of use of which apply to unknown or unlimited populations. The analysis method used is multiple linear regression using SPSS 25 for Windows. This research shows that store atmosphere, product differentiation and service quality partially have a positive influence on purchasing decisions at Mekar Swalayan as evidenced by the significance of the t test value of 0.000 < 0.05. And in the F test store atmosphere, product differentiation and service quality have a simultaneous influence with a significance value of 0.000 < 0.05.