When a mechanical replica of King Kong is unable to dig for the highly radioactive Element X at the North Pole, the evil Doctor Who and his sponsor Madame Piranha (Madame X in the American release) decide to kidnap the real Kong. As an insurance policy they kidnap Lt. Susan Miller as well as her boyfriend Lt. CommanderJiro Nomura and Cmdr. Carl Nelson (Kong developed a crush on Susan when she Nomura and Nelson visited the Kong at his home on Mondo Island). Kong later escapes and heads for Tokyo. Susan and the others also escape. Who and his minions follow him and activate Mechani-Kong in order to recapture him. Susan is then grabbed by the robot and is taken to the top of Tokyo Tower and a battle ensues between Kong and his robotic replica. 60年代的日本人似乎对这个大黑猩猩情有独钟，在玩遍了各种哥斯拉的故事之后，依然将金刚的神奇遭遇不停地向人们展示、炫耀。光看他的故事就能让人吓一跳：科学家制造出了一个机械金刚，用来在北极挖掘神秘的X元素，与此同时邪恶的博士绑架了真正的金刚，令其干同样的活，因此，机械金刚与原形之间的连番恶斗就在所难免了。
