As software systems have been introduced to many advanced applications, the size of software systems increases so much. Simultaneously, the lifetime of software systems becomes very small and thus their development is required to accomplish within relatively short period. In this paper, we propose a new selective software testing method that aims to attain the requirement of short period development. The proposed method consists of 3 steps: Assign priorities to functional modules (Step 1), Derive a test specification (Step 2), and Construct a test plan (Step 3) according to the priorities. In Step 1, for development of functional modules, we select both product and process properties to calculate priorities. Then, in Step 2, we generate detailed test items for each module according to its priority. Finally, in Step 3, we manage test resources including time and developer's skill to attain the requirement. As a result of experimental application, we can show superiority of the proposed testing method to the conventional testing method.