Kanchanaburi is connected by road and rail with Bangkok. Airconditioned and non air-con busses leave Bangkok all day long from the Southern Bus terminal. They depart every 15 minutes from about 5:00 AM to 10:00 PM. The journey can take 2-3 hours.
Trains leave from the Bangkok Noi Railway Station two times a day. You can also get there by booking a minibus with most travel agents in Bangkok.