1. An information processing device, comprising: at least one processor; and at least one memory device that stores a plurality of instructions, which when executed by the at least one processor, causes the at least one processor to operate to: obtain, based on a search criteria input by a user, a plurality of objects that are found as a result of a search with respect to a target category that is one of a plurality of categories which have a tree structure comprising a plurality of hierarchy levels and to each of which one or more objects belong; calculate, in a first search, one of (a) a first value which is the proportion, to a count of lower categories below the target category, of a count of lower categories which are below the B target category and to each of which a count of found objects belongs exceeds a given cutoff threshold; (b) a first value which is the proportion, to a count of lower categories below the target category, of a count of lower categories which are below the target category and to each of which a ratio of a count of found objects belongs divided by a count of found objects belongs to the target category exceeds a given cutoff ratio; and (c) a first value which is variance of a count of found objects among the plurality of categories below the target category; calculate, in a second search which is previous to the first search, one of (a) a second value which is the proportion, to a count of lower categories below the target category, of a count of lower categories which are below the target category and to each of which a count of found objects belongs exceeds a given cutoff threshold; (b) a second value which is the proportion, to a count of lower categories below the target category, of a count of lower categories which are below the target category and to each of which a ratio of a count of found objects belongs divided by a count of found objects belongs to the target category exceeds a given cutoff ratio; and (c) a second value which is variance of a count of found objects among the plurality of categories below the target category; calculate, for the target category, a purchase history count based on a purchase history of the user; calculate, for the target category, a viewing history count based on a viewing history indicating objects of which details are output by detail displaying to the user; calculate, for the target category, a favorites count based on a favorites list in which objects are registered to be viewed later by the user; calculate a degree of use by an expression α×(the purchase history count)+β×(the viewing history count)+γ×(the favorites count) where α, β, and γ are predetermined weighting coefficients and α>β>γ; calculate a weighted addition value by an expression c=S×(the first value)+T×(the degree of use), where S and T are predetermined weighting coefficients; determine whether all of lower categories below the target category is to be displayed or not based on the weighted addition value and a degree of difference between the first value and the second value; control displays to display all of the categories below the target category, based on the determination, wherein, in the weighted addition of the first value and the degree of use, the weighting coefficient T is larger when the purchase history count, the viewing history count, or the favorites count out of the objects that belong to the target category is larger, wherein the weighting coefficient S becomes smaller as the weighting coefficient T becomes larger.