Although the goals of HL7 Version 2(V2) and Version 3(V3) are identical, the concepts of the implementation and technological basis are different; this makes their versions inconvertible. This problem interrupts technological innovation advanced from V2 to V3 and has been raised as a new type of barrier in the field of medical information system. This study intends to develop software to convert V2 to V3 which can be utilized in the actual medical environment. Since it is practically difficult to develop the whole tools that automatically change total V2 messages into V3 messages, this article has designed, implemented, and tested the software that allows mapping between V2 and V3 which function as tools. In order to test this program, it has used ADT^A03 of five V2 messages to generate V3 messages. It is expected that the result of this research will be one of the new methods allowing conversion between V2 and V3.