PURPOSE: To execute the labor saving, automation and high speed of a program preparing work and a test work by incorporating a special means into a computer as software.

CONSTITUTION: A block diagram (m) including a signal system diagram is drawn from an optimum combination (l) such as a module and component which is the result of a program constitution trade off means 2, by a block diagram preparing means 3, and a program trouble mode influence analyzing means 4, at the time of design, forecasts and analyzes the trouble mode such as the nonconformity of a program beforehand prepares an analyzing sheet (n). A software design review means 6 reconsiders the design result of the analyzing sheet (n) and the optimum combination (l). Next, a program test data automatic preparing means 8 prepares the test data (test rule) (p) and a program automatic preparing means 7 prepares a source code (o) of the program. Thus, the labor of the test, the shortening of the test time can be executed and the programming can be efficiently executed.