To provide a cutting tool of an improved structure capable of stably cutting workpieces despite of their shapes.

This cutting tool is provided with: a guide arm 110 positioned rearward in the cutting direction of a movable blade 88 and extending from a support part 52 in the projecting direction of a driving rod 84, the projecting tip portion 132 of the guide arm 110 extending forward in the cutting direction and positioned to turn outward the movable blade 88; a pair of left/right guard members 144 and 144 inward projecting from the projecting tip part 132 of the guide arm 110 toward the movable blade 88, positioned in the both sides of the tip portion 92 having edge part 98 of the movable blade 88 and attached to the guide arm 110 swingably around a swinging shaft, which orthogonally crosses with either of the driving direction or the cutting direction of the movable blade 88; and an energizing means 164 elastically positioning the guide members 144 and 144 in the initial position projecting swingably around the swinging shaft toward the tip portion 92 of the movable blade 88.