The Busan diocesan territory covers 3,267 square kilometers and includes Busan Metropolitan City, Ulsan Metropolitan City, Yangsan City, and parts of Gimhae City and Miryang City in Gyeongsangnam-do province.
Busan diocese belongs to the Ecclesiastical Province of Daegu which comprises Daegu archdiocese, and the dioceses of Andong, Cheongju and Masan. The territory was originally carved out of Daegu archdiocese and made an apostolic vicariate on Jan. 21, 1957. On March 10, 1962, it was elevated to diocese. As of the end of 2005, it had 100 parishes and 392,956 Catholics with 302 priests (according to CBCK statistics).
Visitors to the diocese can see the graveyard of the first Korean martyr, Thomas Kim Bom-woo. He was banished to Miryang, and died in 1786 as a result of severe beating.
Busan diocese arranged to be twinned with Hiroshima diocese of Japan and Infanta diocese of the Philippines in 2001. In 2003, it arranged to be twinned with Taiwan's Kaohsiung diocese.
In Busan diocesan jurisdiction, the population is 5,617,267 at the end of 2015. (Some 11 percent of the whole population 51 million in the country). Most residents are ethnic Koreans.
Standard Korean is in use. English, a mandatory subject in schools, can be spoken and understood in business and tourist areas. All traffic signs are in English and Korean.
Busan diocese falls within the temperate zone and has the four distinctive seasons of spring, summer, autumn and winter. The yearly average temperature of Busan is 13-15 degrees Celsius. The annual precipitation in the region averages 1,200-1,500 millimeters. Most of the rainfall is concentrated in the rainy months (monsoon period) of June through September.
Busan and the Gyeongsangnam-do province are located at the southeastern tip of the Korean peninsula. The region has an average altitude of 500 meters and consists of mountains in the northwest and coastline area in the southeast. Busan is the gateway for Korean foreign trade, has a developed marine industry, and is the second largest city in Korea. Ulsan, one of the seven largest cities in Korea, is known for Hyundai, the Korean automobile manufacturer, and shipbuilding and other heavy industries.