Until the establishment of the Joseon Diocese, the Korean region belonged to the Diocese of Nanjing, China, beginning in 1660. Afterward, in 1792, it became part of the Diocese of Beijing under Bishop Gouvea.

On September 9, 1831, Pope Gregory XVI established the Apostolic Vicariate of Joseon in the Kingdom of Joseon. Its official name is the Apostolic Vicariate of Joseon, though it is generally called the Joseon Diocese.

For eighty years, the Joseon Diocese administered the entire Korean peninsula.

Missionary work was carried out by missionaries of the Paris Foreign Missions Society, notable for spreading the Gospel at the risk of their lives and producing many martyrs.

The first Vicar Apostolic was Bishop Bruguière.

Father Maubant’s achievements include selecting Choe Yang-eop, Choe Bang-je, and Kim Dae-geon to send to the seminary in Macau.

Father Chastan entered the country, learned Korean, traveled throughout villages where believers lived, and administered the sacraments.

Father Maistre took in abandoned infants, raised them, and founded the House of Charity to provide free treatment for the poor. He also promoted clergy formation and established a seminary in Jecheon under the direction of Father Pourthie.

Laypeople’s activities were rooted in the spirit of martyrdom, fraternal charity, and practical virtue.

Evangelization carried out at the cost of their lives became the firm foundation of the Korean Church.

Education given in Catholic villages centered on doctrinal knowledge and prayer life, and strict religious instruction on martyrdom was offered.

During the persecutions, they protected the missionaries.

Lay leaders assisted the missionaries by serving at Mass, preaching, explaining Scripture, and teaching doctrine.

In times of famine they helped the poor, taught the uneducated, cared for the sick, comforted imprisoned believers, and took in abandoned children.

Through these acts of charity they evangelized and strengthened the Church.

The cultural activities of the Joseon Diocese laid the spiritual foundation for Korea’s modernization.

It contributed significantly to Korean linguistics and the spread of Hangeul, and played a social and educational role in instilling a sense of human dignity and equality.

From the 1880s onward, it established various educational institutions and participated in the national enlightenment movement.

Through official Church media such as Kyeonghyang Newspaper, it presented the true direction of modernization.

The religious freedom achieved during the era of the Joseon Diocese became the starting point for establishing freedom of religion and belief in Korea.

Among the spiritual legacies left by the Joseon Diocese, the greatest is the tradition of martyrdom.

• The seventy-nine martyrs of the Byung-o Persecution were beatified in 1925.
• The twenty-four martyrs of the Byung-in Persecution (병인박해, Byung-in Persecution) of 1866were beatified in 1968.
• These 103 Blesseds were canonized on May 6, 1984,by Pope John Paul II during his visit to Korea.

The 103 Martyr Saints are a major spiritual legacy that the Korean Catholic Church, which began with the Apostolic Vicariate of Joseon, has offered to the universal Church.

As of 2023, the Korean Catholic Church is asfollows:

• Faithful: 5,970,675
• Parishes: 1,790
• Mission Stations: 539
• Dioceses (16): Seoul (서울, Seoul), Chuncheon (춘천, Chuncheon),Suwon (수원, Suwon), Daejeon (대전, Daejeon),Uijeongbu (의정부, Uijeongbu), Incheon (인천,Incheon), Wonju (원주, Wonju), Busan (부산, Busan),Cheongju (청주, Cheongju), Masan (마산, Masan),Andong (안동, Andong), Gwangju (광주, Gwangju),Jeonju (전주, Jeonju), Jeju (제주, Jeju),Military Ordinariate (군종, Gunjong)
• Clergy: 5,776