This study compared the perceptions of 548 Korean and Indonesian secondary school teachers in the COVID-19 era and examined factors affecting their intention to continue online learning. Based on survey data, the two countries were compared on seven factors (teaching readiness, challenges and issues, competencies that require training, sources of support, types of support, and endurance). Furthermore, we examined what factors influence the intention to continue online learning. As a result, Korean teachers perceived their teaching readiness for online learning to be less than that of Indonesian teachers. Indonesian teachers perceived that they did not receive sufficient support. Additionally, factors affecting the intention to continue online learning differed depending on the country. Based on these results, we suggested implications for integrating online learning into mathematics education.