Recently, the necessity of analytical method for inverse problems has become much higher because of their usefulness in various application fields, such as non-destructive inspection and so on. Most inverse problems are, however, suffering from ill-posed problems. As a result, they are difficult to solve analytically and uniquely. We have been investigating an estimation of static two-dimensional current distribution in materials, using the observed external magnetic fields as a practical example. By discretizing the above problem, it can be regarded as a combinatorial optimization problem. And we proposed the estimation method by incorporating Genetic Algorithms. Genetic Algorithms are heuristic search algorithms that find solutions to problems based on the mechanism of natural selection. In this paper, we discuss the estimation method for uneven current distribution by devising a coding method. Finally, the feasibility of the proposed method is quantitatively confirmed by simulations.