To provide a cutting tool by which processing such as cutting is performed uniformly, and the processing width such as cutting width is changed to any size, and to provide a blade interval changing mechanism which is used for the cutting tool or the like.

A hand-held cutting tool 1A is used while being held with one hand of a user. The hand-held cutting tool includes: three or more cutter units 2 each having one cutter blade 6, and configured such that the cutter units are movable along the cutter blades 6 provided adjacent to each other; and a blade interval changing device 3 moving the cutter units 2 in the adjacent direction to simultaneously change all of the intervals between the cutter blades 6 in the same amount. The blade interval changing device 3 is allowed to be operated by a user.