In a parallel explosion unit of a parallel explosion apparatus, a processing unit extracts an end product, extracts an assembly directly constituting the end product, and an determines whether or not a BOM tree having the assembly as a vertex is already broken down. When the BOM tree of the assembly is not yet broken down, the processing unit registers the number of units of each component constituting the assembly in an explosion result list and generates a tree-specific list in which the number of units of each component and a registration position of the component in the explosion result list are recorded. When the BOM tree of the assembly is already broken down, the processing unit adds the number of units of each component recorded in the tree-specific list to the number of units at the registration position of the component likewise recorded in the explosion result list.
