Kanchanaburi (Thai: กาญจนบุรี (Pronunciation)) is the largest of the western provinces (changwat) of Thailand. Neighboring provinces are (from north clockwise) Tak, Uthai Thani, Suphan Buri, Nakhon Pathom and Ratchaburi. In the west it borders Kayin State, Mon State and Tanintharyi Region of Myanmar.

It is frequented by tourists who have been attracted by its long history and ancient civilizations, a location of the Bridge over the River Khwae(also spelt ‘Kwai’) and scene of the World War II historic. The province is also famous for its natural attractions such as forests, mountains, caves and waterfalls.

The province is located in the west of Thailand, and is situated 129 km from Bangkok and covers a total area of approximately 19,483 km² being the country’s third largest province after Nakhon Ratchasima and Chiang Mai. Topographically, it is covered with timber and evergreen forests. The district covers the source valleys of the rivers Kwae Yai and Kwae Noi ("River Kwai"), which merge at the city Kanchanaburi and form the Mae Klong River there.

Kanchanaburi (Thai: กาญจนบุรี (Pronunciation)) is a town (thesaban mueang) in the west of Thailand and the capital of Kanchanaburi province. In 2006 it had a population of 31,327. The town covers the complete tambon Ban Nuea and Ban Tai and parts of Pak Phraek and Tha Makham, all of Mueang Kanchanaburi district, and parts of the tambon Tha Lo of Tha Muang district.

Kanchanaburi, which is located where the Khwae Noi and Khwae Yai rivers converge into the Mae Klong river, spans the northern banks of the river and is a popular spot for travelers, its location at the edge of a mountain range keeping it much cooler than the other provinces of central Thailand. The city has two major commercial districts: the downtown area consists of a grid of several streets with office buildings, shop fronts, and a shopping mall; and the riverfront area businesses are mostly located further west along River Kwai Road. Once a year a carnival comes to town and is set up in the area next to the bridge. At night there is a small pyrotechnics display that re-enacts the wartime bombing of the bridge.