In the existing second-hand market, there have been quite a number of unreliable sellers. This has naturally made the market users act defensively when dealing second-hand. To solve this problem, newer transaction methods utilizing escrow services were developed. However, a new problem arose in that transaction fees were imposed only on transacting customers. This obstacle can be overcome through the implementation of a new developed Smart Contract technology. This mechanism enables dealers to make safe oneto-one transactions with other dealers, regardless of their respective locations or identifications. Based on this Blockchain mechanism, ‘J Link coin’ aims to provide potential users with a reliable and safe trading platform for the purposes of second-hand market transactions.