In this century, the intensity of competition and the complications and uncertainties caused by it have made the management of companies to be more sensitive to the use of their financial and non-financial resources, and all their efforts are to spend the resources in a place that will create for the company. to value One of the activities that create value for companies is marketing and advertising activities. Considering the importance of advertising and marketing in the field of product market competition and the relationship it can have with the sales volume of companies, the purpose of this research is to investigate the moderating effect of competitive sales on marketing cost with product sales volume in companies. The statistical population of this research is the companies accepted in the Tehran Stock Exchange and its statistical sample includes the data of 80 companies for a period of 6 years (1395-1400). Multivariable linear regression statistical analyzes were used to test the hypotheses of this research at the 5% error level. The research results show that there is a positive relationship between marketing costs and sales volume, and when marketing costs increase, sales also increase. Also, the research results show that when the competition in the product market increases, the impact of marketing costs on sales also increases.