Abstract: A cutter for optical fibers includes upper and lower frames pivotally connected at their ends pivotally movably relative to each other, a cutting blade provided on the upper frame for cutting optical fibers and supporting device provided on the lower frame for supporting an optical fiber to be cut. The upper frame includes a regulating device for moving the cutting blade in its longitudinal direction and stopping and fixing the cutting blade and a confirming device for visibly confirming a position where the cutting blade is fixed. With this arrangement, there is no need for exchanging of cutting blades every cutting of a fiber. Moreover, a cutting blade portion to be used can be visibly identified and it can be prevented to use again once used cutting edge portion of the cutting blade.