The Design of Experiments (DOE) is a method that is widely used due to its effectiveness in selecting optimum conditions in the design stage of product development. On the other hand, fast, low-cost, labor-saving, and energy-saving innovative development is also required in the industry. In previous research, a program for quickly searching the optimum condition using the design of experiments is developed and evaluated. Relationships between each parameter and the final property are firstly cleared for an algebraic formula by using the design of experiments. Then the optimum conditions for each parameter were decided by using these formulas in the program. However, when each parameter has several errors in the data, the search accuracy becomes very low. In this research, the improvement for the searching accuracy using the law of error propagation was developed and evaluated. Relationships between each parameter error and the final property are firstly cleared for high-accuracy searching by using the law of error propagation and the previous results in the previous research. And each parameter influence for the final property was cleared. It was found that the large parameter effects could be improved for high-precision search by using high-precision instruments, increasing the number of trials N, and taking measurements in an optimal environment. Relationships between each parameter error and the final property were investigated and evaluated for the proposed method by using a mathematical model. It is concluded from the result that (1) the proposed method is effective for clearing the relationships between each parameter error and the final property, and (2) the proposed method is effective for searching the optimum condition.