Manus Boonjumnong (มนัส บุญจำนงค์, born June 23, 1980) is a Thai boxer who won the Olympics at Light Welterweight (64 kg) at the 2004 Summer Olympics . He is the brother of Non Boonjumnong.
In 2006 he made a successful comeback when he was crowned Asian champion. He narrowly defeated reigning 2005 world champion Serik Sapiyev at the tournament although he was knocked down.
In Chicago at the 2007 World Amateur Boxing Championships he was upset early against Japanese Masatsugu Kawachi.