Leptospirosis found in cattle (Bos taurus indicus) has potentially increased in economic impact. The objective was to investigate the factors associated with leptospirosis in cattle in the protected area. We investigated the seroprevalence of leptospirosis in cattle in Salakphra Wildlife Sanctuary, Thailand. Serum was collected to investigate the seroprevalence by agglutination test and their associated factors. From a total of 513 samples, antibodies against Leptospira were detected in 92.2% of samples. Within a total of 42 herds, the serovar with the highest prevalence was L interrogans serovar Tarassovi (92.9%). Most leptospirosis was found in medium-sized herds with the highest concentrations in cattle farms close to cities (52.4%, p < 0.05). Seroprevalence was associated with herd size, raising pattern in the dry and wet seasons, grazing distance, number of years that cattle were kept in the farm, the introduction of new cattle into the farm, and keeping some pets in the farm. The results of the study suggest that keeping cattle in larger herds, raising pattern and distance, keeping period, and introducing new cattle and having pets impart potential risk of increasing leptospirosis exposure. These results indicate that cattle are important hosts of Leptospira in Thailand and may act as sentinels of Leptospira infection for wildlife and people in the protected areas.