To provide a cleaning device of a cutter edge for eliminating the cleaning device from the cutter front-rear side except for cleaning time in a sheet cutter.

A short cutter 7 is lowered from a standby position P1, and when the short cutter 7 returns to the standby position P1 after performing cutting work by lifting the cutter in the vicinity of an upper surface of a work W, a cleaning tool 20 existing in a side retreat position S1 of the left-right outside ends 7e and 8e of the front-rear cutters 7 and 8 simultaneously intrudes inside the long-short cutters 7 and 8 from the right side and the left side, and enters up to the center while cleaning the edge by sandwiching the cutters 7, 8 edges between a cleaning member 22, and returns to the retreat position S1 thereafter.