A syringe device and a method of preparing medicine using the device capable of easily and accurately performing operations for mixing and dissolving a lyophilized product into a dissolution liquid before use. A double ended needle assembly and an intermediate holder are fitted to the first cylindrical part of a connection holder, a first syringe in which the dissolution liquid is stored is inserted into the first cylindrical part through the intermediate holder, and a second syringe in which the lyophilized product is stored in a depressurized state is fixedly inserted into the second cylindrical part of the connection holder. First, the intermediate holder is locked by a finger hooking projected piece, the first syringe is pushed into the intermediate holder in the locked state of the double ended needle assembly at an initial position by locking ribs, and the first syringe is unsealed by one end of the double ended needle. Next, the intermediate holder and the double ended needle assembly are pushed into the first cylindrical part by the first syringe, and the second syringe in the second cylindrical part is unsealed by the other end of the double ended needle.