To provide a cutting edge-replaceable spherical surface cutter which enables a cutting edge of an insert to be arranged at a predetermined location with high precision only by mounting operation of the insert, and prevents the insert from fluctuating caused by cutting resistance occurring during cutting operation.

The cutting edge-replaceable spherical surface cutter is set up by detachably mounting each insert having the arched cutting edge on an insert mounting seat formed in an end face facing the axial direction of a cutter main body that is rotatable in a rotating central axis. Herein the insert abuts on the cutter main body at three points, i.e. a restriction surface of the insert abuts on the mounting seat face of the cutter mounting seat at two points, and the internal peripheral restriction surface of the insert abuts on an internal peripheral side surface of the cutter mounting seat at one point.