The tap tool (10) has an axis of rotation (Cr) and machines a pilot hole (6) so that the same becomes a screw hole (6) in a state where the axis of rotation has been matched to a central axis (C6) of the pilot hole which is provided to a workpiece, wherein the tap tool (10) is characterized by being provided with: a thread section (14) having a blade section (14a) for machining a thread groove of the screw hole; pad sections (15, 16) located behind in a direction of rotation of the blade section, and engaging with the thread groove machined by the blade section during the machining of the thread groove; and a non-engagement section (17) for forming a space (20) between said section and the screw hole in a cross-sectional view where the axis of rotation and the central axis of the screw hole have been matched. The space has a size that enables simultaneous release of the engagement between the thread section and the thread groove and the engagement of the pad sections and the thread groove, in a case where the tap tool has shifted in a direction orthogonal to the axis of rotation within the screw hole, such shift being from the state where the axis of rotation and the central axis of the screw hole have been matched.

A thread repair tool for rethreading a blind tapped hole having damaged threads above undamaged threads of the hole, including: a shaft having a plurality of curved surfaces that extend from a top end of the shaft to a bottom end of the shaft, the plurality of curved surfaces being concave with respect to an exterior perimeter of the shaft; and wherein the shaft has a plurality of corner portions, each one of the plurality of corner portions being located in between two of the plurality of curved surfaces, a first pair of the plurality of corner portions extending from the top end to the bottom end, and a second pair of the plurality of corner portions having a threaded area proximate to the bottom end, the first pair of the plurality of corner portions being adjacent to each other and the second pair of the plurality of corner portions being adjacent to each other.