1. A hierarchical latent variable model estimation device for estimating a hierarchical latent variable model for predicting a supply amount of a product, the hierarchical latent variable model estimation device comprising: a study data input unit for inputting data for study which is a plurality of combinations of a response variable which is a known supply amount of a product and one or more explanatory variables which are information items which can influence the supply amount; a hierarchical latent structure setting unit for setting a hierarchical latent structure that is a structure in which latent variables are represented by a tree structure and components representing probability models are located at nodes of a lowest level of the tree structure; a variational probability computation unit for computing a variational probability of a path latent variable that is a latent variable included in a path linking a root node to a target node in the hierarchical latent structure, based on data for study input by the study data input unit and the components; a component optimization unit for optimizing each of the components for the computed variational probability, based on the data for study input by the study data input unit; and a gating function optimization unit for optimizing a gating function model that is a model for determining a branch direction according to the explanatory variables in a node of the hierarchical latent structure, based on the variational probability of the latent variable in the node.