This paper proposes the Voronoi model-building genetic algorithm (VMBGA), which is one of real-coded GAs. In the VMBGA, a Voronoi model is constructed using with Voronoi diagrams. Because of this mechanism, the distribution of offspring can adapt to the landscape of the objective function by changing the Voronoi model. Through the some standard test functions, the effectiveness of the VMBGA is examined. It is clarified that the VMBGA has higher searching ability than the UNDX-m, which is one of the typical real-coded GAs. Additionally, the distribution of the offspring is also discussed.