In this pandemic, E-Commerce becomes one of the best choices for people to fulfill their needs and wants. Tokopedia, Indonesia's largest E-Commerce application, gains benefits from the increasing number of its monthly web visitor. Unfortunately, recently it suffered from a data breach that leaked most of its user data online, but somehow its monthly web visitor is still rising. This study aims to analyze the importance of E-Commerce security for the users and broadens the understanding of the importance of E-Commerce Security. The data collection was conducted in a quantitative method using an online questionnaire. A self-administered questionnaire (5-point Likert scale) was handed to 384 Tokopedia users using online media. The data were analyzed using Structural Equation Model (SEM). This study finds that although most of the users of Tokopedia can not quite grasp the concept of E-Commerce security, they still think that it is important and it will affect their loyalty towards E-Commerce.