In a modeling method of a neural network, a first regression model is trained based on first sample data and first simulation result data. The first regression model is used to predict the first simulation result data from the first sample data. The first sample data represent at least one of conditions of a manufacturing process of a semiconductor device and characteristics of the semiconductor device. The first simulation result data are obtained by performing a simulation on the first sample data. In response to a consistency of the first regression model being lower than a target consistency, the first regression model is re-trained based on second sample data different from the first sample data. The second sample data are associated with a consistency reduction factor of the first regression model that is responsible for a prediction failure of the first regression model.