Clamping work tool, blade-tip-replaceable cutting tool with clamping work tool, and cutting insert

A clamping tool for attaching a cutting insert to a holder or detaching a cutting insert from a holder, the cutting insert including a head portion having a circular cutting edge with an insert central axis as a center and a shaft portion disposed on a lower side of the head portion in an insert axial direction along the insert central axis, the clamping tool comprising:

• a first jaw portion configured to be locked to the holder;
• and
• an operation lever configured to be connected to the first jaw portion,
• wherein the first jaw portion has
• a locking portion configured to be locked to the holder, and
• a first pressing portion configured to push the head portion downward in the insert axial direction and fit the shaft portion into a shaft hole portion of the holder when the operation lever is rotationally moved in a first direction using the locking portion as a fulcrum.