As there has been increased in technical abuse and illegal to Information devices system product, the conflict is in the copyright ownership issues. A person who involved in development process moved to other company with the important materials of the product illegally, and then he made a similar product compared with first system. it happens to make a lot of loss to first product company. To compare to two product, the copyright association took an estimation to the first product and illegal copy product. At this time, both company must submit all the materials to be referenced to their assistance. because both developer is a person who have a best knowledge to the product. But on most cases, the defender would not willing to submit their development materials as they know their illegal work. So, the estimator do their mission with limited materials and his expert knowledge. In this paper, we tried to suggest a work procedure and extract an estimation factors to helping the verification.