To stick an auxiliary punching instrument to a portion formed at an acute angle with an intersecting rule pressing blade without cutting by use of an instrument such as scissors, and to facilitate sticking work of an auxiliary piece (the auxiliary instrument).

The auxiliary punching instrument 1 for repelling a sheet, which is disposed along a cutting blade 52 in a sheet punch die, is formed of material of a suitable width and a required thickness having cushioning performance, and shaped trapezoidal in a plan view by making both end parts 3, 3 in the longitudinal direction at an acute angle. Thus, the auxiliary instrument 2 can be simply stuck without an obstacle even in a portion arranged in a corner part Q on a board surface formed by disposing the cutting blade 52 and a rule pressing blade 53 intersecting at an acute angle and an inclined shape part of the cutting blade 52.