The implementation of the COVID-19 health protocol is one of the prevention efforts recommended by the government to reduce the transmission of COVID-19 in Indonesia. The market is one of the public places at risk of transmission of COVID-19, but there are still many traders who have not implemented health protocols properly. This study aims to determine the factors related to the behavior of the COVID-19 health protocol on traders at the Oesapa market, Kupang City. This type of research is quantitative research using a cross sectional design. The sample consisted of 100 people with accidental sampling technique. Data analysis used univariate and bivariate analysis with Chi-square test with a significance level of =0.05. The results showed that the factors related to the behavior of the COVID-19 health protocol on traders were age (p-value = 0.007), education level (p-value = 0.000), and level of knowledge (p-value = 0.003), while the unrelated are gender (p-value = 0.967), availability of information sources (p-value = 1,000), and availability of infrastructure (p-value = 0.249). Traders are expected to be able to improve the behavior of the COVID-19 health protocol. Market managers are expected to provide counseling by using posters about preventing COVID-19 in the market area.