The boring tool has a tool body (2) on which a tool carrier (10) is mounted in a radially adjustable manner. A setting member (42) serves to set the boring diameter. A drive mechanism converts a rotation of the setting member (42) into a displacement of the tool carrier (10). The drive mechanism has a differential spindle (13) which converts a rotation of a graduated disk (26) into a displacement of the tool carrier (10) for the fine setting of the boring diameter. The differential spindle (13) is mounted in a bore (51) of the tool carrier (10) and extends at right angles to the rotation axis (A).