It is provided a method for producing a pressure-sensitive adhesive tape or sheet which is superior in a heat-resistance. A mixture is prepared by uniformly mixing a specific polymer having hydrolyzable silyl end groups and urethane linkages and/or urea linkages in the main chains or side chains with tackifying resins. A fluorine-containing compound selected from the group consisting of boron trifluoride, complex of boron trifluoride, fluorinating agent and alkali metal salt of fluorine-containing inorganic acid is uniformly mixed into the mixture to obtain a precursor of a pressure-sensitive adhesive agent. The adhesive precursor is applied on the surface of a tape substrate or sheet substrate. It is obtained a pressure-sensitive adhesive layer having three-dimensional reticulation structures by curing the specific polymer having hydrolyzable silyl end groups. Thereby, it is obtained the pressure-sensitive adhesive tape or sheet.