The purpose of this research is (1) To study the decision to buy a secondhand car of consumer in Rangsit, Pathumthani. (2) to To study the decision to buy a secondhand car of consumer in Rangsit , Pathumthani. Classification based on personal factors. And (3) to study factor in 7P's of the Marketing Mix with affecting decision to buy a secondhand car of consumer in Rangsit, Pathumthani. Population of the research sample are consumers aged 18 years and over living in Rangsit, Pathumthani. the number of samples, 400 people. Using a random sample by random coincidence. The tools used in this research was .questionnaire to study the decision to buy a secondhand car of consumer in Rangsit, Pathumthani. Has reliability 0.79 and statistical analysis by using Percentage ,Standard deviation (S.D.) , T-test ,One-way ANOVA and Regression Analysis.