Swimming at the 2005 World Aquatics Championships – Men's 100 metre breaststroke

The Men's 100 Breaststroke event at the 11th FINA World Aquatics Championships swam 24 and 25 July 2005 in Montreal, Canada. Preliminary and semifinal heats were swum 24 July; finals on July 25.

At the start of the event, the existing World (WR) and Championships (CR) records were:
 * WR: 59.30 swum by Brendan Hansen (USA) on July 8, 2004, in Long Beach, USA
 * CR: 59.78 swum by Kosuke Kitajima (Japan) on July 21, 2003, in Barcelona, Spain