Startup Store is one of the commercial stores in the city of Palembang that sells various used laptops and cellphone accessories. However, this store has several obstacles, namely in terms of sales, which still use the manual method where customers come directly to the store, choose goods and then pay for them at the cashier, after that the cashier writes in the sales report book. To solve this problem, the Startup Store store requires an E-commerce that can help process the sales transaction online, where customers do not need to come directly to the store. In designing an E-Commerce Startup Store, the right method is needed in its development. Therefore, the prototype method was chosen because it has the ability to support the stages of a good system design process. The results of this study indicate that the designed E-Commerce can support the sales transaction process and its reporting well. Keywords: E-commerce, Prototype