Migraine is an enormous burden on society, but relevant studies are limited. The population of interest of this study was migraine or probable migraine (PM) in Korea. In this population, we aimed to assess the productivity loss through the level of severity defined by monthly migraine days (MMD) and analgesic frequency and to estimate costs and associated factors of productivity loss. We conducted an online survey of adults with migraine symptoms. We defined migraine and PM using the modified International Classification of Headache Disorders, second edition. Severity level was defined by subgroups of MMD (0-3, 4-14, and ≥15 days) and analgesic frequency (0, 1, 2, 3, and ≥4 per week). Productivity loss was assessed using the Work Productivity and Activity Impairment questionnaire and consisted of absenteeism, presenteeism, overall work productivity loss, and activity impairment. The costs of productivity loss due to absenteeism and presenteeism were calculated in 2020 USD. We used negative binomial regression to identify the factors associated with the costs of productivity loss. We identified 362 respondents with migraine or PM. Mean age was 41.7 years, 75.7% were female (N = 274), and 73.2% (N = 265) were employed. On average, productivity losses due to absenteeism and presenteeism were 8.1% and 39.7%, respectively. As MMD increased, there was a trend toward increased activity impairment, presenteeism, and overall work productivity loss. The mean overall productivity loss cost was USD 44.61 per person per day. Duration of migraine attacks was significantly associated with higher absenteeism costs. The results of this study indicate that the higher the MMD, the greater the productivity loss in patients with migraine or PM in Korea. We also found that patients with low-frequency migraine and PM experienced substantial productivity loss. This study provides comprehensive evidence of the burden of migraine in Korea using a representative sample.