Sanmen County (Tai-chow dialect: Sæn-meng Yön; Simplified Chinese: 三门县; Hanyu Pinyin: Sānmén Xiàn) is a county under the jurisdiction of Taizhou city/Municipality in Zhejiang Province of the People's Republic of China. The county's total area is 1072 square kilometers, and its population is 400,000 people. The county's postal code is 317100.