The men's 100 metre breaststroke event at the 2005 World Aquatics Championships took place between 24 July and 25 July. The heats and semifinals were held 24 July. The final was held 25 July.

Records

Prior to the competition, the existing world and championship records were as follows.

	Name	Nationality	Time	Location	Date
World record	Brendan Hansen Brendan Hansen Brendan Joseph Hansen is an American breaststroke swimmer and four-time Olympic medalist...	United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district...	59.30	Long Beach Long Beach, California Long Beach is a city situated in Los Angeles County in Southern California, on the Pacific coast of the United States. The city is the 36th-largest city in the nation and the seventh-largest in California. As of 2010, its population was 462,257...	8 July 2004
Championship record	Kosuke Kitajima Kosuke Kitajima is a Japanese multiple Olympic gold medalist breaststroke swimmer. He won gold medals for the men's 100 m and 200 m breaststroke at both the Athens 2004 and Beijing 2008 Olympics.-Major achievements:...	Japan Japan Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...	59.78	Barcelona Barcelona Barcelona is the second largest city in Spain after Madrid, and the capital of Catalonia, with a population of 1,621,537 within its administrative limits on a land area of...	21 July 2003

The following records were established during the competition:

Date	Round	Name	Nationality	Time	WR	CR
July 24	Heats	Kosuke Kitajima Kosuke Kitajima is a Japanese multiple Olympic gold medalist breaststroke swimmer. He won gold medals for the men's 100 m and 200 m breaststroke at both the Athens 2004 and Beijing 2008 Olympics.-Major achievements:...	Japan Japan Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...	59.71		CR
July 25	Final	Brendan Hansen Brendan Hansen Brendan Joseph Hansen is an American breaststroke swimmer and four-time Olympic medalist...	United States United States The United States of America is a federal constitutional republic comprising fifty states and a federal district...	59.37		CR

Final

Rank	Name	Nationality	Time	Notes
	Brendan Hansen Brendan Hansen Brendan Joseph Hansen is an American breaststroke swimmer and four-time Olympic medalist...		59.37	CR
	Kosuke Kitajima Kosuke Kitajima is a Japanese multiple Olympic gold medalist breaststroke swimmer. He won gold medals for the men's 100 m and 200 m breaststroke at both the Athens 2004 and Beijing 2008 Olympics.-Major achievements:...		59.53
	Hugues Duboscq Hugues Duboscq Hugues Duboscq is an Olympic breaststroke swimmer from France. He swam for France at the 2000, 2004 and 2008 Olympics. He has won three Olympic bronze medals....		1:00.20
4	Oleg Lisogor Oleg Lisogor Oleh Lisohor is a Ukrainian swimmer.Born in Brovary, Kiev Oblast, Soviet Union , Lisogor is the former world record holder in the 50 metres breaststroke, long course, with 27.18 seconds. The record was set in Berlin on 2 August 2002...		1:00.36
5	Dmitry Komornikov		1:00.66
6	Chris Cook		1:00.99
7	Alexander Dale Oen Alexander Dale Oen Alexander Dale Oen is a Norwegian swimmer. He represents the club Vestkantsvømmerne. Dale Oen's gold at the 2008 European Championships made him the first Norwegian male to win a medal at a major international long course championship.Oen got his international breakthrough in 2005, placing seventh...		1:01.29
8	Emil Tahirovič Emil Tahirovic Emil Tahirovič is an Olympic breaststroke swimmer from Slovenia. He swam for Slovenia at the 2000 and 2004 Olympics.He swam for Slovenia at:*Olympics: 2000, 2004*Mediterranean Games: 2005, 2009...		1:01.33

Key: CR = Championship record