A liquid-phase blocking ELISA (LPBE) was developed to detect antibodies against foot-and-mouth disease virus (FMDV) serotype A in pigs. The LPBE used inactivated 146S viral particles from the A/Yeoncheon/SKR/2017 strain as the antigen. The LPBE showed high diagnostic sensitivity of 92.1% and specificity of 88.6% compared to the virus neutralization test. A total of 133 pig sera were evaluated, demonstrating good correlation between the two tests. The LPBE performed better than the solid-phase ELISA currently used in South Korea, with higher sensitivity and equivalent specificity for monitoring the immune response to FMDV vaccination.