Adrenal diseases are quite common in Japanese pet ferrets; however, there have been no reports concerning the epidemiology of ferret adrenal disease in Japan. The purpose of this study was to collect epidemiological data on ferret adrenal disease in Japan by sending a questionnaire to veterinarians throughout Japan. Among the 521 cases that met the criteria for this study, 307 were adrenocortical carcinoma (58.9%), 117 were adrenocortical adenoma (22.5%) and 87 were adrenocortical hyperplasia (16.7%), respectively. Sex, clinical signs, concurrent diseases, age and the sites of the affected adrenal gland in these cases were similar to those reported in North America. Most pet ferrets in Japan are imported from North America, and their husbandry in Japan is similar to that in North America, which may be the cause of the similarity in ferret adrenal disease between North America and Japan. Because a difference in the incidence of ferret adrenal diseases among countries has been reported, further research is necessary to investigate the factors related to the similarities and how to decrease the incidence of adrenal diseases in ferrets in Japan.