According to the research, consumer’s buying behavior of BEC students at Thammasat University was studied. The main aim of this research is to investigate how discount product has influenced customer’s purchasing. In addition, this research’s objective is to identify the reasons behind the consumer’s purchase of discount product. Moreover, it was conducted to determine the factors that stimulate people to buy discount product and also assess the buyers’ opinion about discount product. The reason for doing this research is that the researcher wants to understand the reasons why many people like to buy product on sale and how it affects to the purchasing of buyers. For the method, the sample of 30 people was selected from students in BEC program, Thammasat University. The result of this survey revealed that most people like to buy products during sale season. Discount product is useful for consumer because they pay for the products in cheaper price than usual. They also confirm that discount product is necessary for their life. Many of them said that discount product has same quality, but it is paid in less price. The research is divided into five main parts which are introduction, literature review, method, result and conclusion that will be presented as follows.