Abstract: A learning device creates a plurality of decision trees, using pieces of training data respectively including an explanatory variable and an objective variable, which are configured by a combination of the explanatory variables and respectively estimate the objective variable based on true or false of the explanatory variables. The learning device creates a linear model that is equivalent to the plurality of decision trees, and lists all terms configured by a combination of the explanatory variables without omission. The learning device outputs a prediction result by using the linear model from input data.