To provide a cutter capable of improving the working accuracy of a cut surface of a material to be cut by reducing the positional shifting of a cutting position.

This cutter 1 includes a fixed plate 2 secured to a base 11, a rotary plate 3 and a driving part 4 for rotating the rotary plate 3. A gas pipe 30 is passed through an insert hole 21 of the fixed plate 2 and an insert hole 42 of the rotary plate 3. A pair of upper and lower chucks 23a, 23b are disposed on the fixed plate 2 movably in the radial direction of the fixed plate 2. According to the outside diameter of the gas pipe 30, a pair of upper and lower chucks 23a, 23b are justified along the radial direction of the gas pipe 30 according to the outside diameter of the gas pipe 30 and the gas pipe 30 is removably clamped and fixed by the paired upper and lower chucks 23a, 23b. When a driving shaft 12 is rotated, the rotary plate 3 is rotated through a driving gear 14 and a rack 41, so that the gas pipe 30 is cut along the radial direction by a cutting blade 58.