Hashimoto's disease was named after Japanese surgeon Hakaru Hashimoto of Kyushu University, who reported the disease in a German medical journal for the first time anywhere in the world in 1912. From the perspective of the disease's condition, Hashimoto's disease is also referred to as "chronic thyroiditis," which means chronic inflammation of the thyroid gland. Women are more susceptible to thyroid disorders than men. Of all the thyroid disorders, Hashimoto's disease is particularly common in women and they are almost 20-30 times more susceptible to the disease than men. In respect to the age groups of patients, the disease is most likely to develop in the late 20s or later, especially in the 30s and 40s. Hashimoto's disease very rarely occurs in infants and school children.

Hashimoto's disease, which is characterized by inflammation of the thyroid gland, does not show inflammation marked by the formation of pus due to invading bacteria, but is caused by the abnormality known as "autoimmunity." Autoimmunity can trigger several disorders, but it is still unknown how it occurs. Hashimoto's disease is considered to occur when one form of lymphocytes attacks the thyroid tissue.