The present invention is concerned with a thermal delayed tack composition which is non-adhesive at ordinary temperatures but can be activated and tackified when heated and can maintain its tackiness for a long period of time even after separated from a heat source, and thermal delayed tack sheets prepared by coating basic sheets with this thermal delayed tack composition and then drying the same. The thermal delayed tack sheets have the features that even when they are wound into a roll or superimposed upon each other, no blocking or sticking occurs, and that the tackiness thereof can be maintained for a long period of time even upon a plastic material such as for example polyethylene having low polarity. The aforesaid thermal delayed tack composition comprises an aqueous resin dispersion containing, as fundamental components, solid components of (a) 100 parts by weight of a polymer resin containing 1% by weight or more of carboxylic acid-modified polyethylene, (b) 10 to 120 parts by weight of a tackifier, and (c) 50 to 300 parts by weight of a solid plasticizer. Furthermore, the aforesaid thermal delayed tack sheets may be prepared by aqueously coating the basic sheets with the above-mentioned composition and then drying the same.