To provide sleeve material that can easily change its configuration in compliance with installation position of a form.

In forming a penetration hole in a concrete slab, a plurality of expected configuration lines 33-38 to adjust the size to meet the installation position of the form are preliminary indicated on the sleeve body 11. The form has irreguralities, and the sleeve is sometimes installed astride over a protrusion, a recess or the protrusion and the recess. The respective expected configuration lines 33 to 38 indicate lines for cutting the sleeve body 11 by a cutter such as scissors, cutter to change the shape of the sleeve body 11 in accordance with the size and the installation position of the form. Hence, site workers can easily change the sleeve configuration by cutting the sleeve body 11 along the line 33 to 38 to match the setting place.