A method of manufacturing cooling storage units and a sales management system is to be provided for the same permitting the exclusion of a made-to-order production system which indispensably requires pre-shipment cooling tests. Thermally insulated boxes of different predetermined sets of specifications, each usable as a freezer, a refrigerator, or a freezer-refrigerator, and cooling units so fabricated as to have a prescribed cooling capacity for any one of the group of thermally insulated boxes are made ready in advance. One thermally insulated box, meeting the specified requirements from the group of thermally insulated boxes, and a matching cooling unit are transported to the installation site of the cooling storage unit. The thermally insulated box and the cooling unit are combined at the installation site to constitute the cooling storage unit.