The purpose of this study was to research hats for pyeonbok that were worn by Joseon's diplomatic delegate to Japan, that is, Tongsinsa since the 18th century, with references to the collection of conversations in writing and exchanged poems and paintings, literature, including Sahaengrok, and other paintings all of which are related to Tongsinsa. The findings of the study can be summarized as follows. First, the members of Tongsinsa that were delegated to Japan in the late Joseon Period included three leading officials or samsa, chief official interpreter or dangsang yeokgwan, general official interpreters or yeokgwan, high literary officials or jesulgwan, clerks or seogi, medical specialists or yangeui, physicians or euiwon, official dictators or sajagwan and official painters or hwawon. All these members wore pyeonbokpo when being on board at sea or staying at lodgings. At the same time, they wore hats for pyeonbok. Second, hats that the diplomatic delegates usually wore when dressed in pyeonbok include waryonggwan, jeongjagwan, dongpagwan, gohugwan, bokgeon, yeonyeopgwan, yukja unyeopgwan, banggwan, gosagwan, hwayanggeon and tanggeon. Among these, jeongjagwan, dongpagwan, gohugwan and tanggeon were often worn by delegate members of different positions. Third, the members of Tongsinsa prepared in advance hats for pyeonbok which allow them to properly appear themselves as Confucianists and keep easily with. Each member often carried a few of the hats and chose from them, whichever was more convenient. Fourth, the collection of conversations in writing and exchanged poems and paintings includes a relatively fewer conversations that samsa made in writing. Records about hats for pyeonbok that are found in that collection are only about waryonggwan and bokgeon. This is because it was in most cases jesulgwan, seogi, yangeui or euiwon who communicated with Japanese by writing. However, it is presumed that samsa also wore different types of hats for pyeonbok including waryonggwan and bokgeon.