To provide a self-traveling cutting machine for cutting protrusions of a suspended piece and the like.

The cutting machine 11 for cutting protrusions protruded from a steel part 12 includes: four attaching parts 13 detachably attached to the steel part 12; rail guide supports 14 erected to the attaching parts 13; moving rails 15 provided over the rail guide supports 14; guide plates 16 movable along the moving rails 15; an attachment base plate 17 continuously provided at the guide plates 16 and having a cutting opening for passing the protrusions therethrough at a center; a drive motor 18 provided at the attachment base plate 17; a driving roller 19 driven linked with the drive of the drive motor 18 and provided at the attachment base plate 17; a pair of driven rollers 20 provided at the attachment base plate 17 while facing the driving roller 19; a cutter 21 rotated by the driven rollers 20 and the driving roller 19; and a towing means 22 towing the attachment base plate 17 along the moving rails 15.