The 14th century Sinan (or Shinan) Shipwreck, located in the southwestern marine area of the Korean peninsula, is one of the most significant ancient shipwrecks in the East Asian seas. Several hypotheses have been proposed about the port of departure, although insufficient archaeological research has been carried out on this matter. This paper makes a detailed comparison between the ceramics found on the Sinan shipwreck and the contemporaneous ceramics unearthed in Fuzhou, Hangzhou, and Ningbo in China, using three parameters: places of origin, proportion of products from different kilns, and similarity in ware types. We confirm that the most likely departure port of the ship was Ningbo (at that time called Qingyuan), from the perspective of its ceramic cargo. This inspires us to re-evaluate the importance of Ningbo to the maritime trade in the East Asian seas.