A double-sided heat-sensitive adhesive sheet comprises a support provided with a release layer on one side thereof and heat-sensitive adhesive layers which are formed on both sides of the support and have sufficient adhesion to the support but can be easily peeled apart from the release layer, wherein the release layer and the heat-sensitive adhesive layer has at their interface a 180null peeling resistance of 10-30 g/50 mm in a peel test performed at a peeling speed of 500 mm/min. in an atmosphere of 20null C. and 65% RH. The adhesive sheet is interposed between each opposed pair of information-recorded faces of recording material having on one side at least two spaces for information-recording, and heat is applied to the resultant assembly to make a laminate. The laminate can have a size and weight suitable for mailing as a postcard, and can bear confidential information on the inside and be peeled apart when desired.