To certainly detect that a temporarily storing member is certainly attached to a predetermined position in a device and whether or not an amount of filing member accumulated in the temporarily storing member reaches to a predetermined amount in a sheet post-processing device having a means for cutting a part of the filing member and the member for temporarily storing the cut filing member.

It is detected that a needle scrap box 60 is attached to a device body and that displacement of a mechanism displaced with position is performed when a predetermined amount of needles is accumulated in the needle scrap box 60 using one detection means 62. Thereby, two different states can be detected by one detection means.