The aim of development Purchase Tansaction application at SitusNet Global Soution Inc. is to substitute the old Transaction system and Inventory Management system with the new one so that the Purchase Transaction and Inventory process in small and medium enterprise will be better. To fulfill the purpose, many features is added like Graphical User Interface based system and automatic reports maker to make the Inventory system in small and medium enterprise better. This new application consists of several features like purchase transaction, item grouping, item stock, warehouse, various report, application authority, multicurrency , data searching , etc. The Purchase Tansaction application for small and medum enterprise is developed using EMS Interbase Firebird Manager 3 as database management system, Borland Delphi 5 as programming language tool, and Fast Report 3.0 for making reports.