An object of the present invention is to provide a heat-insulating sleeve with reduced deformation possibility of short strips resulting from interference at lock-forming portions. Part of the heat-insulating sleeve 120 above or below a plurality of short strips 121 and 122 is slid to cause the short strips 121 and 122 to bend or curve and to project radially outward, thereby creating a heat-insulating grip. The short strips 121 and 122 include alternately arranged first short strips 121 and second short strips 122. At least one of slits 130 has a lock-forming portion 131 that is to form a projected portion 127 and a recessed portion 128 in the short strips 121 and 122. The short strips 121 and 122 each include a constricted portion having a left-to-right width set smaller than the widths of parts located above or below same. Mountain folds 124 and 126 are formed in the respective constricted portions of the short strips 121 and 122.
