外表落魄邋遢的浪人武士三十郎(三船敏郎 饰)来到一个小镇,清兵卫(河津清三郎 饰)和新田丑寅(山茶花究 饰)两家恶霸在那里为争夺地盘,招兵买马经常争斗,弄得民不聊生。三十郎决定从中设计,引诱双方雇佣自己,再加入不同方造成两边拼斗,由此坐收渔利,消灭对方。 但随着丑寅弟弟卯之助(仲代达矢 饰)的加入,情况又发生了不同,他手里握有短枪,占得优势,清兵卫的势力被打败,三十郎甚至也受伤不轻。但是决战在所难免,椿三十郎独对丑寅、亥之吉等众人,身处劣势的他如何能剿灭对方呢?Sanjuro, a wandering samurai enters a rural town in nineteenth century Japan. After learning from the innkeeper that the town is divided between two gangsters, he plays one side off against the other. His efforts are complicated by the arrival of the wily Unosuke, the son of one of the gangsters, who owns a revolver. Unosuke has Sanjuro beaten after he reunites an abducted woman with her husband and son, then massacres his father's opponents. During the slaughter, the samurai escapes with the help of the innkeeper; but while recuperating at a nearby temple, he learns of innkeeper's abduction by Unosuke, and returns to the town to confront him.