To make it easy to mount and demount a tool such as a cutting blade, a line and a sewing machine blade with regard to a baseplate and to make it possible to discover forgetting of mounting of the tool at the time of mounting.

The composition of a trimming die is such that a cutting blade 86 for punching a sheet material is narrowly inserted into a fixed groove 87 formed in a baseplate 81 to be fixed. In this case, the baseplate 81 has a baseplate proper 82 and a relatively thin face plate 83 which is removably attached to one face side of the baseplate proper 82, and the fixed groove 87 is formed passing through the baseplate proper 82 and the face plate 83, as well as the cutting blade 86 is mounted straddling the baseplate proper 82 and the face plate 83 with its blade base being on the face plate side.