To provide a work cutting device capable of suppressing unevenness of assembling accuracy caused by a foreign matter adhering to a contact face between a cutter blade and a spacer when reassembling the work cutting device.

This cutting device has the rotary blades 2, 4, 6; and the spacers 3, 5 fixed to the rotary blades 2, 4, 6 with the spacers 3, 5 contacted with the rotary blades 2, 4, 6, having grooves 3a, 5a for storing the foreign matter formed in faces contacting with the rotary blades 2, 4, 6.